From: Joe Simmons-Talbott <josimmon@redhat.com>
To: libc-alpha@sourceware.org
Cc: Joe Simmons-Talbott <josimmon@redhat.com>
Subject: [PATCH] getipv4sourcefilter: Get rid of alloca
Date: Tue, 30 May 2023 14:32:55 -0400 [thread overview]
Message-ID: <20230530183255.637210-1-josimmon@redhat.com> (raw)
Use a scratch_buffer rather than alloca to avoid potential stack
overflows.
---
sysdeps/unix/sysv/linux/getipv4sourcefilter.c | 24 ++++++-------------
1 file changed, 7 insertions(+), 17 deletions(-)
diff --git a/sysdeps/unix/sysv/linux/getipv4sourcefilter.c b/sysdeps/unix/sysv/linux/getipv4sourcefilter.c
index 8a367b1048..ce72becead 100644
--- a/sysdeps/unix/sysv/linux/getipv4sourcefilter.c
+++ b/sysdeps/unix/sysv/linux/getipv4sourcefilter.c
@@ -16,9 +16,9 @@
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 <scratch_buffer.h>
#include <string.h>
#include <stdint.h>
#include <netinet/in.h>
@@ -33,17 +33,12 @@ getipv4sourcefilter (int s, struct in_addr interface, struct in_addr group,
/* We have to create an struct ip_msfilter object which we can pass
to the kernel. */
socklen_t needed = IP_MSFILTER_SIZE (*numsrc);
- int use_alloca = __libc_use_alloca (needed);
- struct ip_msfilter *imsf;
- if (use_alloca)
- imsf = (struct ip_msfilter *) alloca (needed);
- else
- {
- imsf = (struct ip_msfilter *) malloc (needed);
- if (imsf == NULL)
- return -1;
- }
+ struct scratch_buffer buf;
+ scratch_buffer_init (&buf);
+ if (!scratch_buffer_set_array_size (&buf, 1, needed))
+ return -1;
+ struct ip_msfilter *imsf = buf.data;
imsf->imsf_multiaddr = group;
imsf->imsf_interface = interface;
@@ -61,12 +56,7 @@ getipv4sourcefilter (int s, struct in_addr interface, struct in_addr group,
*numsrc = imsf->imsf_numsrc;
}
- if (! use_alloca)
- {
- int save_errno = errno;
- free (imsf);
- __set_errno (save_errno);
- }
+ scratch_buffer_free (&buf);
return result;
}
--
2.39.2
next reply other threads:[~2023-05-30 18:33 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-30 18:32 Joe Simmons-Talbott [this message]
2023-05-31 12:37 ` Adhemerval Zanella Netto
2023-06-01 14:20 ` Joe Simmons-Talbott
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