Headline
CVE-2021-44339: heap-buffer-overflow in function ok_png_transform_scanline() at ok_png.c:712:13 · Issue #15 · brackeen/ok-file-formats
David Brackeen ok-file-formats 203defd is vulnerable to Buffer Overflow. When the function of the ok-file-formats project is used, a heap-buffer-overflow occurred in function ok_png_transform_scanline() in "/ok_png.c:712".
Version
203defd
Environment
Ubuntu 18.04,64 bit
Testcase
#include <stdio.h> #include <stdlib.h> #include “ok_png.c” #include “ok_png.h”
int main(int _argc, char **_argv) { FILE *file = fopen(_argv[1], “rb”); ok_png image = ok_png_read(file, OK_PNG_COLOR_FORMAT_RGBA ); fclose(file); if (image.data) { printf("Got image! Size: %li x %li\n", (long)image.width, (long)image.height); free(image.data); } return 0; }
Command
Compile test program:
$ gcc -g -o main main.c ok_png.h
Compile test program with address sanitizer with this command:
$ gcc -g -fsanitize=address -o asanpng main.c ok_png.h
Result
The result of running without ASAN:
$ ./main heap-buffer-overflow-3.png
free(): invalid pointer
Aborted (core dumped)
Information obtained by using ASAN:
$ ./asanpng heap-buffer-overflow-3.png
==8813==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x621000002680 at pc 0x0000004e48dc bp 0x7ffe51b2f890 sp 0x7ffe51b2f888
WRITE of size 4 at 0x621000002680 thread T0
#0 0x4e48db in ok_png_transform_scanline /docker/ok-file-formats-png/ok_png.c:712:13
#1 0x4e48db in ok_png_read_data /docker/ok-file-formats-png/ok_png.c:895:13
#2 0x4e48db in ok_png_decode2 /docker/ok-file-formats-png/ok_png.c:971:23
#3 0x4e48db in ok_png_decode /docker/ok-file-formats-png/ok_png.c:1025:5
#4 0x4e81d5 in ok_png_read_with_allocator /docker/ok-file-formats-png/ok_png.c:188:9
#5 0x4e81d5 in ok_png_read /docker/ok-file-formats-png/ok_png.c:177:12
#6 0x4e81d5 in main /docker/ok-file-formats-png/main.c:8:20
#7 0x7fe87e6f50b2 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x270b2)
#8 0x41c38d in _start (/docker/ok-file-formats-png/afl_asan+0x41c38d)
0x621000002680 is located 384 bytes to the right of 4096-byte region [0x621000001500,0x621000002500)
allocated by thread T0 here:
#0 0x4975ed in malloc (/docker/ok-file-formats-png/afl_asan+0x4975ed)
#1 0x4cd004 in ok_png_read_data /docker/ok-file-formats-png/ok_png.c:774:29
#2 0x4cd004 in ok_png_decode2 /docker/ok-file-formats-png/ok_png.c:971:23
#3 0x4cd004 in ok_png_decode /docker/ok-file-formats-png/ok_png.c:1025:5
#4 0x4e81d5 in ok_png_read_with_allocator /docker/ok-file-formats-png/ok_png.c:188:9
#5 0x4e81d5 in ok_png_read /docker/ok-file-formats-png/ok_png.c:177:12
#6 0x4e81d5 in main /docker/ok-file-formats-png/main.c:8:20
#7 0x7fe87e6f50b2 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x270b2)
SUMMARY: AddressSanitizer: heap-buffer-overflow /docker/ok-file-formats-png/ok_png.c:712:13 in ok_png_transform_scanline
Shadow bytes around the buggy address:
0x0c427fff8480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0c427fff8490: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0c427fff84a0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c427fff84b0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c427fff84c0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
=>0x0c427fff84d0:[fa]fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c427fff84e0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c427fff84f0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c427fff8500: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c427fff8510: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c427fff8520: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
Shadow byte legend (one shadow byte represents 8 application bytes):
Addressable: 00
Partially addressable: 01 02 03 04 05 06 07
Heap left redzone: fa
Freed heap region: fd
Stack left redzone: f1
Stack mid redzone: f2
Stack right redzone: f3
Stack after return: f5
Stack use after scope: f8
Global redzone: f9
Global init order: f6
Poisoned by user: f7
Container overflow: fc
Array cookie: ac
Intra object redzone: bb
ASan internal: fe
Left alloca redzone: ca
Right alloca redzone: cb
Shadow gap: cc
==8813==ABORTING
Description
A heap-buffer-overflow was discovered in ok_file_formats. The issue is being triggered in function ok_png_transform_scanline() at ok_png.c:712:13.
Poc
Poc file is this.