* [PATCH v2] setsourcefilter: Use malloc() rather than alloca().
@ 2023-05-15 19:08 Joe Simmons-Talbott
2023-05-16 11:09 ` Adhemerval Zanella Netto
0 siblings, 1 reply; 3+ messages in thread
From: Joe Simmons-Talbott @ 2023-05-15 19:08 UTC (permalink / raw)
To: libc-alpha; +Cc: Joe Simmons-Talbott
To prevent possible stack overflow use malloc() rather than alloca().
---
Changes to v1:
- don't save and restore errno around free()
sysdeps/unix/sysv/linux/setsourcefilter.c | 20 ++++----------------
1 file changed, 4 insertions(+), 16 deletions(-)
diff --git a/sysdeps/unix/sysv/linux/setsourcefilter.c b/sysdeps/unix/sysv/linux/setsourcefilter.c
index 538f4de696..2823168d34 100644
--- a/sysdeps/unix/sysv/linux/setsourcefilter.c
+++ b/sysdeps/unix/sysv/linux/setsourcefilter.c
@@ -16,7 +16,6 @@
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 <string.h>
@@ -34,17 +33,11 @@ setsourcefilter (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. */
size_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;
- }
+ gf = (struct group_filter *) malloc (needed);
+ if (gf == NULL)
+ return -1;
gf->gf_interface = interface;
memcpy (&gf->gf_group, group, grouplen);
@@ -63,12 +56,7 @@ setsourcefilter (int s, uint32_t interface, const struct sockaddr *group,
else
result = __setsockopt (s, sol, MCAST_MSFILTER, gf, needed);
- if (! use_alloca)
- {
- int save_errno = errno;
- free (gf);
- __set_errno (save_errno);
- }
+ free (gf);
return result;
}
--
2.39.2
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH v2] setsourcefilter: Use malloc() rather than alloca().
2023-05-15 19:08 [PATCH v2] setsourcefilter: Use malloc() rather than alloca() Joe Simmons-Talbott
@ 2023-05-16 11:09 ` Adhemerval Zanella Netto
2023-05-16 13:51 ` Joe Simmons-Talbott
0 siblings, 1 reply; 3+ messages in thread
From: Adhemerval Zanella Netto @ 2023-05-16 11:09 UTC (permalink / raw)
To: Joe Simmons-Talbott, libc-alpha
On 15/05/23 16:08, Joe Simmons-Talbott via Libc-alpha wrote:
> To prevent possible stack overflow use malloc() rather than alloca().
> ---
> Changes to v1:
> - don't save and restore errno around free()
>
> sysdeps/unix/sysv/linux/setsourcefilter.c | 20 ++++----------------
> 1 file changed, 4 insertions(+), 16 deletions(-)
>
> diff --git a/sysdeps/unix/sysv/linux/setsourcefilter.c b/sysdeps/unix/sysv/linux/setsourcefilter.c
> index 538f4de696..2823168d34 100644
> --- a/sysdeps/unix/sysv/linux/setsourcefilter.c
> +++ b/sysdeps/unix/sysv/linux/setsourcefilter.c
> @@ -16,7 +16,6 @@
> 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 <string.h>
> @@ -34,17 +33,11 @@ setsourcefilter (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. */
> size_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;
> - }
> + gf = (struct group_filter *) malloc (needed);
> + if (gf == NULL)
> + return -1;
>
> gf->gf_interface = interface;
> memcpy (&gf->gf_group, group, grouplen);
> @@ -63,12 +56,7 @@ setsourcefilter (int s, uint32_t interface, const struct sockaddr *group,
> else
> result = __setsockopt (s, sol, MCAST_MSFILTER, gf, needed);
>
> - if (! use_alloca)
> - {
> - int save_errno = errno;
> - free (gf);
> - __set_errno (save_errno);
> - }
> + free (gf);
>
> return result;
> }
Maybe we can use a scratch_buffer to avoid always use malloc:
diff --git a/sysdeps/unix/sysv/linux/setsourcefilter.c b/sysdeps/unix/sysv/linux/setsourcefilter.c
index 538f4de696..22b307ca80 100644
--- a/sysdeps/unix/sysv/linux/setsourcefilter.c
+++ b/sysdeps/unix/sysv/linux/setsourcefilter.c
@@ -16,13 +16,10 @@
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 <string.h>
-#include <stdint.h>
#include <netinet/in.h>
-#include <sys/socket.h>
+#include <scratch_buffer.h>
#include "getsourcefilter.h"
@@ -34,17 +31,11 @@ setsourcefilter (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. */
size_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);
@@ -63,12 +54,7 @@ setsourcefilter (int s, uint32_t interface, const struct sockaddr *group,
else
result = __setsockopt (s, sol, MCAST_MSFILTER, gf, needed);
- if (! use_alloca)
- {
- int save_errno = errno;
- free (gf);
- __set_errno (save_errno);
- }
+ scratch_buffer_free (&buf);
return result;
}
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH v2] setsourcefilter: Use malloc() rather than alloca().
2023-05-16 11:09 ` Adhemerval Zanella Netto
@ 2023-05-16 13:51 ` Joe Simmons-Talbott
0 siblings, 0 replies; 3+ messages in thread
From: Joe Simmons-Talbott @ 2023-05-16 13:51 UTC (permalink / raw)
To: Adhemerval Zanella Netto; +Cc: libc-alpha
On Tue, May 16, 2023 at 08:09:13AM -0300, Adhemerval Zanella Netto wrote:
>
>
> On 15/05/23 16:08, Joe Simmons-Talbott via Libc-alpha wrote:
> > To prevent possible stack overflow use malloc() rather than alloca().
> > ---
> > Changes to v1:
> > - don't save and restore errno around free()
> >
> > sysdeps/unix/sysv/linux/setsourcefilter.c | 20 ++++----------------
> > 1 file changed, 4 insertions(+), 16 deletions(-)
> >
> > diff --git a/sysdeps/unix/sysv/linux/setsourcefilter.c b/sysdeps/unix/sysv/linux/setsourcefilter.c
> > index 538f4de696..2823168d34 100644
> > --- a/sysdeps/unix/sysv/linux/setsourcefilter.c
> > +++ b/sysdeps/unix/sysv/linux/setsourcefilter.c
> > @@ -16,7 +16,6 @@
> > 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 <string.h>
> > @@ -34,17 +33,11 @@ setsourcefilter (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. */
> > size_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;
> > - }
> > + gf = (struct group_filter *) malloc (needed);
> > + if (gf == NULL)
> > + return -1;
> >
> > gf->gf_interface = interface;
> > memcpy (&gf->gf_group, group, grouplen);
> > @@ -63,12 +56,7 @@ setsourcefilter (int s, uint32_t interface, const struct sockaddr *group,
> > else
> > result = __setsockopt (s, sol, MCAST_MSFILTER, gf, needed);
> >
> > - if (! use_alloca)
> > - {
> > - int save_errno = errno;
> > - free (gf);
> > - __set_errno (save_errno);
> > - }
> > + free (gf);
> >
> > return result;
> > }
>
> Maybe we can use a scratch_buffer to avoid always use malloc:
>
> diff --git a/sysdeps/unix/sysv/linux/setsourcefilter.c b/sysdeps/unix/sysv/linux/setsourcefilter.c
> index 538f4de696..22b307ca80 100644
> --- a/sysdeps/unix/sysv/linux/setsourcefilter.c
> +++ b/sysdeps/unix/sysv/linux/setsourcefilter.c
> @@ -16,13 +16,10 @@
> 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 <string.h>
> -#include <stdint.h>
> #include <netinet/in.h>
> -#include <sys/socket.h>
> +#include <scratch_buffer.h>
> #include "getsourcefilter.h"
>
>
> @@ -34,17 +31,11 @@ setsourcefilter (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. */
> size_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);
> @@ -63,12 +54,7 @@ setsourcefilter (int s, uint32_t interface, const struct sockaddr *group,
> else
> result = __setsockopt (s, sol, MCAST_MSFILTER, gf, needed);
>
> - if (! use_alloca)
> - {
> - int save_errno = errno;
> - free (gf);
> - __set_errno (save_errno);
> - }
> + scratch_buffer_free (&buf);
>
> return result;
> }
>
Thanks for the suggestion. This patch is now superseded by a new patch
[1]
Thanks,
Joe
[1] https://sourceware.org/pipermail/libc-alpha/2023-May/148146.html
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2023-05-15 19:08 [PATCH v2] setsourcefilter: Use malloc() rather than alloca() Joe Simmons-Talbott
2023-05-16 11:09 ` Adhemerval Zanella Netto
2023-05-16 13:51 ` Joe Simmons-Talbott
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