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* [glibc] setsourcefilter: Replace alloca with a scratch_buffer.
@ 2023-05-29 13:19 Siddhesh Poyarekar
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From: Siddhesh Poyarekar @ 2023-05-29 13:19 UTC (permalink / raw)
To: glibc-cvs
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=d9055634a34d4bcb242f84f36c9a7bb1c4019076
commit d9055634a34d4bcb242f84f36c9a7bb1c4019076
Author: Joe Simmons-Talbott <josimmon@redhat.com>
Date: Tue May 16 09:45:49 2023 -0400
setsourcefilter: Replace alloca with a scratch_buffer.
Use a scratch_buffer rather than either alloca or malloc to reduce the
possibility of a stack overflow.
Suggested-by: Adhemerval Zanella Netto <adhemerval.zanella@linaro.org>
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Diff:
---
sysdeps/unix/sysv/linux/setsourcefilter.c | 27 +++++++--------------------
1 file changed, 7 insertions(+), 20 deletions(-)
diff --git a/sysdeps/unix/sysv/linux/setsourcefilter.c b/sysdeps/unix/sysv/linux/setsourcefilter.c
index 538f4de696..479744f169 100644
--- a/sysdeps/unix/sysv/linux/setsourcefilter.c
+++ b/sysdeps/unix/sysv/linux/setsourcefilter.c
@@ -16,13 +16,10 @@
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
-#include <alloca.h>
#include <errno.h>
-#include <stdlib.h>
#include <string.h>
-#include <stdint.h>
#include <netinet/in.h>
-#include <sys/socket.h>
+#include <scratch_buffer.h>
#include "getsourcefilter.h"
@@ -34,17 +31,12 @@ setsourcefilter (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. */
size_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);
@@ -63,12 +55,7 @@ setsourcefilter (int s, uint32_t interface, const struct sockaddr *group,
else
result = __setsockopt (s, sol, MCAST_MSFILTER, gf, needed);
- if (! use_alloca)
- {
- int save_errno = errno;
- free (gf);
- __set_errno (save_errno);
- }
+ scratch_buffer_free (&buf);
return result;
}
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