| Message ID | 20230511150915.2468745-1-josimmon@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | setsourcefilter: Use malloc() rather than alloca(). | expand |
On 11/05/23 12:09, Joe Simmons-Talbott via Libc-alpha wrote: > To prevent possible stack overflow use malloc() rather than alloca(). > --- > sysdeps/unix/sysv/linux/setsourcefilter.c | 22 ++++++---------------- > 1 file changed, 6 insertions(+), 16 deletions(-) > > diff --git a/sysdeps/unix/sysv/linux/setsourcefilter.c b/sysdeps/unix/sysv/linux/setsourcefilter.c > index 538f4de696..6678572968 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 +56,9 @@ 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); > - } > + int save_errno = errno; > + free (gf); > + __set_errno (save_errno); > > return result; > } free now must preserve errno (check 69fda43b8dd795c3658869633ca0708ed3134006), so there is no need to save/restore it. The rest looks ok for me.
On Mon, May 15, 2023 at 03:35:10PM -0300, Adhemerval Zanella Netto wrote: > > > On 11/05/23 12:09, Joe Simmons-Talbott via Libc-alpha wrote: > > To prevent possible stack overflow use malloc() rather than alloca(). > > --- > > sysdeps/unix/sysv/linux/setsourcefilter.c | 22 ++++++---------------- > > 1 file changed, 6 insertions(+), 16 deletions(-) > > > > diff --git a/sysdeps/unix/sysv/linux/setsourcefilter.c b/sysdeps/unix/sysv/linux/setsourcefilter.c > > index 538f4de696..6678572968 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 +56,9 @@ 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); > > - } > > + int save_errno = errno; > > + free (gf); > > + __set_errno (save_errno); > > > > return result; > > } > > free now must preserve errno (check 69fda43b8dd795c3658869633ca0708ed3134006), > so there is no need to save/restore it. The rest looks ok for me. > Thanks. Fixed in v2. Joe
diff --git a/sysdeps/unix/sysv/linux/setsourcefilter.c b/sysdeps/unix/sysv/linux/setsourcefilter.c index 538f4de696..6678572968 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 +56,9 @@ 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); - } + int save_errno = errno; + free (gf); + __set_errno (save_errno); return result; }