getsourcefilter: Get rid of alloca.
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Commit Message
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(-)
Comments
On 30/05/23 15:13, 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/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;
> }
On Wed, May 31, 2023 at 09:27:30AM -0300, Adhemerval Zanella Netto wrote:
>
>
> On 30/05/23 15:13, 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>
Thanks for the review. Would you mind committing this please?
Thanks,
Joe
>
> > ---
> > 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;
> > }
>
@@ -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;
}