https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107746
Bug ID: 107746
Summary: gcc -O1 misses a stack-buffer-overflow
Product: gcc
Version: 13.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: sanitizer
Assignee: unassigned at gcc dot gnu.org
Reporter: shaohua.li at inf dot ethz.ch
CC: dodji at gcc dot gnu.org, dvyukov at gcc dot gnu.org,
jakub at gcc dot gnu.org, kcc at gcc dot gnu.org, marxin at
gcc dot gnu.org
Target Milestone: ---
For the following code, `gcc-trunk -O1 -fsanitize=address` misses the
stack-buffer-overflow, while `gcc-trunk -Ox -fsanitize=address` (x=0,2,3, or s)
can detect it.
Maybe fundamentally similar to
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107698 but that was a miss of
global-buffer-overflow.
Compiler explorer: https://godbolt.org/z/PxWs76fqf
% cat a.c
int a;
short b;
short *c = &b;
int *d = &a;
void main() {
int e;
*d = 0;
d = &e + 3;
*d = --*c;
}
% gcc-tk -O1 -fsanitize=address a.c && ./a.out
%
% gcc-tk -O3 -fsanitize=address a.c && ./a.out
=================================================================
==1==ERROR: AddressSanitizer: stack-buffer-overflow on address 0x7f074300002c
at pc 0x0000004011b1 bp 0x7fffa6d6a4d0 sp 0x7fffa6d6a4c8
WRITE of size 4 at 0x7f074300002c thread T0
#0 0x4011b0 in main /app/example.c:9
#1 0x7f0745a17082 in __libc_start_main
(/lib/x86_64-linux-gnu/libc.so.6+0x24082) (BuildId:
1878e6b475720c7c51969e69ab2d276fae6d1dee)
#2 0x40125d in _start (/app/output.s+0x40125d) (BuildId:
c0151d5ad34e416e89a8cfe01d6f2ea794b64dec)
Address 0x7f074300002c is located in stack of thread T0 at offset 44 in frame
#0 0x4010bf in main /app/example.c:5
This frame has 1 object(s):
[32, 36) 'e' (line 6) <== Memory access at offset 44 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 /app/example.c:9 in main
Shadow bytes around the buggy address:
0x7f0742fffd80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x7f0742fffe00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x7f0742fffe80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x7f0742ffff00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x7f0742ffff80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x7f0743000000: f1 f1 f1 f1 04[f3]f3 f3 00 00 00 00 00 00 00 00
0x7f0743000080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x7f0743000100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x7f0743000180: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x7f0743000200: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x7f0743000280: 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
==1==ABORTING
%
