Public bug reported:
Binary package hint: gcc-4.2
The following source, without the "(void*)" overrides, will throw an
warning (as expected), when compiled with -Wall:
$ gcc -o memcpy-fortify -Wall memcpy-fortify.c
memcpy-fortify.c: In function 'main':
memcpy-fortify.c:21: warning: passing argument 1 of 'memcpy' discards
qualifiers from pointer target type
memcpy-fortify.c:22: warning: passing argument 1 of 'strcpy' discards
qualifiers from pointer target type
With "(void*)" it is (as expected) silent. With -O2, it is silent, but
with -D_FORTIFY_SOURCE != 0, the qualifier override is ignored:
$ gcc -o memcpy-fortify -Wall -O2 -D_FORTIFY_SOURCE=2 memcpy-fortify.c
memcpy-fortify.c: In function 'main':
memcpy-fortify.c:21: warning: passing argument 1 of 'memcpy' discards
qualifiers from pointer target type
memcpy-fortify.c:22: warning: passing argument 1 of 'strcpy' discards
qualifiers from pointer target type
This will cause problems for builds that run with -Werror.
/*
* gcc -o memcpy-fortify -Wall -Werror -O2 -D_FORTIFY_SOURCE=2 memcpy-fortify.c
*
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdint.h>
#include <string.h>
#include <stdint.h>
#include <inttypes.h>
int main(int argc, char * argv[])
{
char *foo = strdup("string one");
char *bar = strdup("string two");
const char *baz = (const char *)foo;
printf("%s\n", foo);
memcpy((void*)baz, bar, strlen(bar)+1);
strcpy((void*)baz, bar);
printf("%s\n", foo);
return 0;
}
** Affects: gcc-4.2 (Ubuntu)
Importance: Undecided
Status: New
--
-D_FORTIFY_SOURCE discards qualifier overrides in {mem,str}cpy
https://bugs.launchpad.net/bugs/217481
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