* [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 ^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2023-05-16 13:51 UTC | newest] Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 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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