From: Adhemerval Zanella Netto <adhemerval.zanella@linaro.org>
To: Joe Simmons-Talbott <josimmon@redhat.com>, libc-alpha@sourceware.org
Subject: Re: [PATCH] getipv4sourcefilter: Get rid of alloca
Date: Wed, 31 May 2023 09:37:15 -0300 [thread overview]
Message-ID: <6d5ebc02-0b95-ef6a-d01b-edfcfed92a8b@linaro.org> (raw)
In-Reply-To: <20230530183255.637210-1-josimmon@redhat.com>
On 30/05/23 15:32, Joe Simmons-Talbott via Libc-alpha wrote:
> Use a scratch_buffer rather than alloca to avoid potential stack
> overflows.
LGTM, thanks.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
> ---
> 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;
> }
next prev parent reply other threads:[~2023-05-31 12:37 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-30 18:32 Joe Simmons-Talbott
2023-05-31 12:37 ` Adhemerval Zanella Netto [this message]
2023-06-01 14:20 ` Joe Simmons-Talbott
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