[glibc] getsourcefilter: Get rid of alloca.
Adhemerval Zanella
azanella@sourceware.org
Thu Jun 1 17:49:09 GMT 2023
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=d1eaab5a7932cda190cbbfa657c684059b141c19
commit d1eaab5a7932cda190cbbfa657c684059b141c19
Author: Joe Simmons-Talbott <josimmon@redhat.com>
Date: Tue May 30 14:13:40 2023 -0400
getsourcefilter: Get rid of alloca.
Use a scratch_buffer rather than alloca to avoid potential stack
overflows.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Diff:
---
sysdeps/unix/sysv/linux/getsourcefilter.c | 24 +++++++-----------------
1 file changed, 7 insertions(+), 17 deletions(-)
diff --git a/sysdeps/unix/sysv/linux/getsourcefilter.c b/sysdeps/unix/sysv/linux/getsourcefilter.c
index b9ba58c23a..461ad889a9 100644
--- a/sysdeps/unix/sysv/linux/getsourcefilter.c
+++ b/sysdeps/unix/sysv/linux/getsourcefilter.c
@@ -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;
}
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