From: Joe Simmons-Talbott <josimmon@redhat.com>
To: libc-alpha@sourceware.org
Cc: Joe Simmons-Talbott <josimmon@redhat.com>
Subject: [PATCH] getsourcefilter: Get rid of alloca.
Date: Tue, 30 May 2023 14:13:40 -0400 [thread overview]
Message-ID: <20230530181340.3926125-1-josimmon@redhat.com> (raw)
Use a scratch_buffer rather than alloca to avoid potential stack
overflows.
---
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;
}
--
2.39.2
next reply other threads:[~2023-05-30 18:13 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-30 18:13 Joe Simmons-Talbott [this message]
2023-05-31 12:27 ` Adhemerval Zanella Netto
2023-06-01 14:21 ` Joe Simmons-Talbott
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20230530181340.3926125-1-josimmon@redhat.com \
--to=josimmon@redhat.com \
--cc=libc-alpha@sourceware.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).