https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108628
Bug ID: 108628
Summary: ASAN at -O3 misses a stack-use-after-return
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, ASAN at -O3 missed the stack-use-after-return, while
other opt levels detected it.
Clang at all opt levels can detect it.
Compiler explorer: https://godbolt.org/z/q5ezG1MK3
% cat a.c
int *a;
int **b = &a;
char c;
int d, g;
void h(int i) {
long e[112];
e;
int *f = &i;
a = f;
}
void j() {
char *k[12];
for (; d; d++)
k[g] = &c;
}
int main() {
j();
h(-1);
__builtin_printf("**b=%d\n", **b);
}
%
% gcc-tk -fsanitize=address -O3 a.c && ./a.out
**b=-1
%
% gcc-tk -fsanitize=address -O2 a.c && ./a.out
=================================================================
==1==ERROR: AddressSanitizer: stack-use-after-return on address 0x7f0646b00020
at pc 0x000000401148 bp 0x7ffed3f9a190 sp 0x7ffed3f9a188
READ of size 4 at 0x7f0646b00020 thread T0
#0 0x401147 in main /a.c:19
#1 0x7f064954c082 in __libc_start_main
(/lib/x86_64-linux-gnu/libc.so.6+0x24082) (BuildId:
1878e6b475720c7c51969e69ab2d276fae6d1dee)
#2 0x4011ad in _start (/output.s+0x4011ad) (BuildId:
7b9e8ee9f7af16e4a0a8a05fef54777844619617)
Address 0x7f0646b00020 is located in stack of thread T0 at offset 32 in frame
#0 0x40127f in h /a.c:5
This frame has 1 object(s):
[32, 36) 'i' (line 5) <== Memory access at offset 32 is inside 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-use-after-return /a.c:19 in main
Shadow bytes around the buggy address:
0x7f0646affd80: 00 00 00 00 00 00
...
%
