Use __pthread_attr_copy in mq_notify (bug 27896)

Message ID 874keiaryl.fsf@igel.home
State New
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Series
  • Use __pthread_attr_copy in mq_notify (bug 27896)
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Commit Message

Andreas Schwab June 1, 2021, 8:50 a.m.
Make a deep copy of the pthread attribute object to remove a potential
use-after-free issue.
---
 NEWS                                |  4 ++++
 sysdeps/unix/sysv/linux/mq_notify.c | 15 ++++++++++-----
 2 files changed, 14 insertions(+), 5 deletions(-)

-- 
2.31.1


-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510  2552 DF73 E780 A9DA AEC1
"And now for something completely different."

Comments

Siddhesh Poyarekar June 1, 2021, 1:55 p.m. | #1
On 6/1/21 2:20 PM, Andreas Schwab wrote:
> Make a deep copy of the pthread attribute object to remove a potential

> use-after-free issue.


LGTM

Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>


> ---

>   NEWS                                |  4 ++++

>   sysdeps/unix/sysv/linux/mq_notify.c | 15 ++++++++++-----

>   2 files changed, 14 insertions(+), 5 deletions(-)

> 

> diff --git a/NEWS b/NEWS

> index 266837bf2d..4460752df7 100644

> --- a/NEWS

> +++ b/NEWS

> @@ -56,6 +56,10 @@ Security related changes:

>     potentially resulting in degraded service or Denial of Service on the

>     local system.  Reported by Chris Schanzle.

>   

> +  CVE-2021-33574: The mq_notify function has a potential use-after-free

> +  issue when using a notification type of SIGEV_THREAD and a thread

> +  attribute with a non-default affinity mask.

> +

>   The following bugs are resolved with this release:

>   

>     [The release manager will add the list generated by

> diff --git a/sysdeps/unix/sysv/linux/mq_notify.c b/sysdeps/unix/sysv/linux/mq_notify.c

> index cc575a0cdd..f7ddfe5a6c 100644

> --- a/sysdeps/unix/sysv/linux/mq_notify.c

> +++ b/sysdeps/unix/sysv/linux/mq_notify.c

> @@ -133,8 +133,11 @@ helper_thread (void *arg)

>   	    (void) __pthread_barrier_wait (&notify_barrier);

>   	}

>         else if (data.raw[NOTIFY_COOKIE_LEN - 1] == NOTIFY_REMOVED)

> -	/* The only state we keep is the copy of the thread attributes.  */

> -	free (data.attr);

> +	{

> +	  /* The only state we keep is the copy of the thread attributes.  */

> +	  pthread_attr_destroy (data.attr);

> +	  free (data.attr);

> +	}

>       }

>     return NULL;

>   }

> @@ -255,8 +258,7 @@ mq_notify (mqd_t mqdes, const struct sigevent *notification)

>         if (data.attr == NULL)

>   	return -1;

>   

> -      memcpy (data.attr, notification->sigev_notify_attributes,

> -	      sizeof (pthread_attr_t));

> +      __pthread_attr_copy (data.attr, notification->sigev_notify_attributes);

>       }

>   

>     /* Construct the new request.  */

> @@ -270,7 +272,10 @@ mq_notify (mqd_t mqdes, const struct sigevent *notification)

>   

>     /* If it failed, free the allocated memory.  */

>     if (__glibc_unlikely (retval != 0))

> -    free (data.attr);

> +    {

> +      pthread_attr_destroy (data.attr);

> +      free (data.attr);

> +    }

>   

>     return retval;

>   }

>

Patch

diff --git a/NEWS b/NEWS
index 266837bf2d..4460752df7 100644
--- a/NEWS
+++ b/NEWS
@@ -56,6 +56,10 @@  Security related changes:
   potentially resulting in degraded service or Denial of Service on the
   local system.  Reported by Chris Schanzle.
 
+  CVE-2021-33574: The mq_notify function has a potential use-after-free
+  issue when using a notification type of SIGEV_THREAD and a thread
+  attribute with a non-default affinity mask.
+
 The following bugs are resolved with this release:
 
   [The release manager will add the list generated by
diff --git a/sysdeps/unix/sysv/linux/mq_notify.c b/sysdeps/unix/sysv/linux/mq_notify.c
index cc575a0cdd..f7ddfe5a6c 100644
--- a/sysdeps/unix/sysv/linux/mq_notify.c
+++ b/sysdeps/unix/sysv/linux/mq_notify.c
@@ -133,8 +133,11 @@  helper_thread (void *arg)
 	    (void) __pthread_barrier_wait (&notify_barrier);
 	}
       else if (data.raw[NOTIFY_COOKIE_LEN - 1] == NOTIFY_REMOVED)
-	/* The only state we keep is the copy of the thread attributes.  */
-	free (data.attr);
+	{
+	  /* The only state we keep is the copy of the thread attributes.  */
+	  pthread_attr_destroy (data.attr);
+	  free (data.attr);
+	}
     }
   return NULL;
 }
@@ -255,8 +258,7 @@  mq_notify (mqd_t mqdes, const struct sigevent *notification)
       if (data.attr == NULL)
 	return -1;
 
-      memcpy (data.attr, notification->sigev_notify_attributes,
-	      sizeof (pthread_attr_t));
+      __pthread_attr_copy (data.attr, notification->sigev_notify_attributes);
     }
 
   /* Construct the new request.  */
@@ -270,7 +272,10 @@  mq_notify (mqd_t mqdes, const struct sigevent *notification)
 
   /* If it failed, free the allocated memory.  */
   if (__glibc_unlikely (retval != 0))
-    free (data.attr);
+    {
+      pthread_attr_destroy (data.attr);
+      free (data.attr);
+    }
 
   return retval;
 }