Attachment 13606 Details for Bug 28213 – Proposed patch

[patch] Proposed patch

0001-librt-fix-NULL-pointer-dereference-bug-28213.patch (text/plain), 1.52 KB, created by Nikita Popov on 2021-08-09 12:29:31 UTC

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Creator: Nikita Popov

Created: 2021-08-09 12:29:31 UTC

Size: 1.52 KB

patch

obsolete

>From c69f990e356dd8e756b0025e026d59db5af6e059 Mon Sep 17 00:00:00 2001
>From: Nikita Popov <npv1310@gmail.com>
>Date: Mon, 9 Aug 2021 17:15:52 +0500
>Subject: [PATCH] librt: fix NULL pointer dereference (bug 28213)
>To: libc-alpha@sourceware.org
>
>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).
>---
> 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 (&notify_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);
>-- 
>2.17.1
>

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