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- From b805aebd42364fe696e417808a700fdb9800c9e8 Mon Sep 17 00:00:00 2001
- From: Nikita Popov <npv1310@gmail.com>
- Date: Mon, 9 Aug 2021 20:17:34 +0530
- Subject: [PATCH] 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).
- Upstream-Status: Backport [https://sourceware.org/git/?p=glibc.git;a=commit;h=b805aebd42364fe696e417808a700fdb9800c9e8]
- CVE: CVE-2021-38604
- Signed-off-by: Nikita Popov <npv1310@gmail.com>
- Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
- Signed-off-by: Vinay Kumar <vinay.m.engg@gmail.com>
- ---
- 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 9799dcdaa4..eccae2e4c6 100644
- --- a/sysdeps/unix/sysv/linux/mq_notify.c
- +++ b/sysdeps/unix/sysv/linux/mq_notify.c
- @@ -131,7 +131,7 @@ 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);
- --
- 2.31.1
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