https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80638
Bug ID: 80638
Summary: -ansi suppresses -Wstringop-overflow for mempcpy
Product: gcc
Version: 7.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: msebor at gcc dot gnu.org
Target Milestone: ---
A program containing a buffer overflow in a call to mempcpy compiled with the
-ansi option GCC is not diagnosed. The same program is diagnosed without the
option, or when the call to mempcpy is replaced with memcpy.
Calls to known library functions that overflow should be diagnosed regardless
of -ansi.
$ (set -x && cat a.c && for opt in '' -ansi; do gcc -O2 -S -Wall $opt a.c;
done)
+ cat a.c
extern void* mempcpy (void*, const void*, __SIZE_TYPE__);
char d[3];
void f (void)
{
mempcpy (d, "1234", 5);
}
+ for opt in ''\'''\''' -ansi
+ gcc -O2 -S -Wall a.c
a.c: In function ‘f’:
a.c:7:3: warning: ‘mempcpy’ writing 5 bytes into a region of size 3 overflows
the destination [-Wstringop-overflow=]
mempcpy (d, "1234", 5);
^~~~~~~~~~~~~~~~~~~~~~
+ for opt in ''\'''\''' -ansi
+ gcc -O2 -S -Wall -ansi a.c
$
