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From 217b6dc298156bdb0d6aea9ea93e7e394a5ff091 Mon Sep 17 00:00:00 2001
From: Florian Weimer <fweimer@redhat.com>
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 <siddhesh@sourceware.org>
https://sourceware.org/bugzilla/attachment.cgi?id=13497
Upstream-Status: Backport
CVE: CVE-2021-33574 patch#2
Signed-off-by: Armin Kuster <akuster@mvista.com>
---
Index: git/sysdeps/unix/sysv/linux/mq_notify.c
===================================================================
--- git.orig/sysdeps/unix/sysv/linux/mq_notify.c
+++ git/sysdeps/unix/sysv/linux/mq_notify.c
@@ -260,7 +260,34 @@ mq_notify (mqd_t mqdes, const struct sig
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 sig
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);
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