From 217b6dc298156bdb0d6aea9ea93e7e394a5ff091 Mon Sep 17 00:00:00 2001 From: Florian Weimer Date: Tue, 1 Jun 2021 17:51:41 +0200 Subject: [PATCH] Fix use of __pthread_attr_copy in mq_notify (bug 27896) __pthread_attr_copy can fail and does not initialize the attribute structure in that case. If __pthread_attr_copy is never called and there is no allocated attribute, pthread_attr_destroy should not be called, otherwise there is a null pointer dereference in rt/tst-mqueue6. Fixes commit 42d359350510506b87101cf77202fefcbfc790cb ("Use __pthread_attr_copy in mq_notify (bug 27896)"). Reviewed-by: Siddhesh Poyarekar note that this patch has few modifications to adapt glibc2.28 Conflict:NA Reference:https://sourceware.org/git/?p=glibc.git;a=commit;h=217b6dc298156bdb0d6aea9ea93e7e394a5ff091 --- sysdeps/unix/sysv/linux/mq_notify.c | 31 +++++++++++++++++++++++++++-- 1 file changed, 29 insertions(+), 2 deletions(-) diff --git a/sysdeps/unix/sysv/linux/mq_notify.c b/sysdeps/unix/sysv/linux/mq_notify.c index c4091169..76963567 100644 --- a/sysdeps/unix/sysv/linux/mq_notify.c +++ b/sysdeps/unix/sysv/linux/mq_notify.c @@ -260,7 +260,34 @@ mq_notify (mqd_t mqdes, const struct sigevent *notification) if (data.attr == NULL) return -1; - __pthread_attr_copy (data.attr, notification->sigev_notify_attributes); + memcpy (data.attr, notification->sigev_notify_attributes, + sizeof (pthread_attr_t)); + + struct pthread_attr *source = + (struct pthread_attr *) (notification->sigev_notify_attributes); + struct pthread_attr *target = (struct pthread_attr *) (data.attr); + cpu_set_t *newp; + cpu_set_t *cpuset = source->cpuset; + size_t cpusetsize = source->cpusetsize; + + /* alloc a new memory for cpuset to avoid use after free */ + if (cpuset != NULL && cpusetsize > 0) + { + newp = (cpu_set_t *) malloc (cpusetsize); + if (newp == NULL) + { + free(data.attr); + return -1; + } + + memcpy (newp, cpuset, cpusetsize); + target->cpuset = newp; + } + else + { + target->cpuset = NULL; + target->cpusetsize = 0; + } } /* Construct the new request. */ @@ -273,7 +300,7 @@ mq_notify (mqd_t mqdes, const struct sigevent *notification) int retval = INLINE_SYSCALL (mq_notify, 2, mqdes, &se); /* If it failed, free the allocated memory. */ - if (__glibc_unlikely (retval != 0)) + if (retval != 0 && data.attr != NULL) { pthread_attr_destroy (data.attr); free (data.attr); -- 2.23.0