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getsourcefilter: Get rid of alloca.

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Use a scratch_buffer rather than alloca to avoid potential stack
overflows.
Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
This commit is contained in:
Joe Simmons-Talbott 2023-05-30 14:13:40 -04:00 committed by Adhemerval Zanella
parent 29e25f6f13
commit d1eaab5a79
1 changed files with 7 additions and 17 deletions
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24
sysdeps/unix/sysv/linux/getsourcefilter.c
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@ -16,10 +16,10 @@
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <alloca.h>
#include <assert.h>
#include <errno.h>
#include <stdlib.h>
#include <scratch_buffer.h>
#include <string.h>
#include <stdint.h>
#include <netatalk/at.h>
@ -95,17 +95,12 @@ getsourcefilter (int s, uint32_t interface, const struct sockaddr *group,
/* We have to create an struct ip_msfilter object which we can pass
to the kernel. */
socklen_t needed = GROUP_FILTER_SIZE (*numsrc);
int use_alloca = __libc_use_alloca (needed);
struct group_filter *gf;
if (use_alloca)
gf = (struct group_filter *) alloca (needed);
else
{
gf = (struct group_filter *) malloc (needed);
if (gf == NULL)
return -1;
}
struct scratch_buffer buf;
scratch_buffer_init (&buf);
if (!scratch_buffer_set_array_size (&buf, 1, needed))
return -1;
struct group_filter *gf = buf.data;
gf->gf_interface = interface;
memcpy (&gf->gf_group, group, grouplen);
@ -135,12 +130,7 @@ getsourcefilter (int s, uint32_t interface, const struct sockaddr *group,
}
}
if (! use_alloca)
{
int save_errno = errno;
free (gf);
__set_errno (save_errno);
}
scratch_buffer_free (&buf);
return result;
}