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* [glibc/release/2.32/master] librt: fix NULL pointer dereference (bug 28213)
@ 2021-08-17 13:52 Siddhesh Poyarekar
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From: Siddhesh Poyarekar @ 2021-08-17 13:52 UTC (permalink / raw)
To: glibc-cvs
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=76dfec932475fa1a8751149520fa39bc4bbc9125
commit 76dfec932475fa1a8751149520fa39bc4bbc9125
Author: Nikita Popov <npv1310@gmail.com>
Date: Mon Aug 9 20:17:34 2021 +0530
librt: fix NULL pointer dereference (bug 28213)
Helper thread frees copied attribute on NOTIFY_REMOVED message
received from the OS kernel. Unfortunately, it fails to check whether
copied attribute actually exists (data.attr != NULL). This worked
earlier because free() checks passed pointer before actually
attempting to release corresponding memory. But
__pthread_attr_destroy assumes pointer is not NULL.
So passing NULL pointer to __pthread_attr_destroy will result in
segmentation fault. This scenario is possible if
notification->sigev_notify_attributes == NULL (which means default
thread attributes should be used).
Signed-off-by: Nikita Popov <npv1310@gmail.com>
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
(cherry picked from commit b805aebd42364fe696e417808a700fdb9800c9e8)
Diff:
---
sysdeps/unix/sysv/linux/mq_notify.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/sysdeps/unix/sysv/linux/mq_notify.c b/sysdeps/unix/sysv/linux/mq_notify.c
index b5a903c3a2..2bb98172c8 100644
--- a/sysdeps/unix/sysv/linux/mq_notify.c
+++ b/sysdeps/unix/sysv/linux/mq_notify.c
@@ -132,7 +132,7 @@ helper_thread (void *arg)
to wait until it is done with it. */
(void) __pthread_barrier_wait (¬ify_barrier);
}
- else if (data.raw[NOTIFY_COOKIE_LEN - 1] == NOTIFY_REMOVED)
+ else if (data.raw[NOTIFY_COOKIE_LEN - 1] == NOTIFY_REMOVED && data.attr != NULL)
{
/* The only state we keep is the copy of the thread attributes. */
pthread_attr_destroy (data.attr);
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