Fix use of __pthread_attr_copy in mq_notify (bug 27896)

Message ID 87wnrd1nor.fsf@oldenburg.str.redhat.com
State New
Headers show
Series
  • Fix use of __pthread_attr_copy in mq_notify (bug 27896)
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Commit Message

Szabolcs Nagy via Libc-alpha June 1, 2021, 5:48 p.m.
__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)").

Tested on i686-linux-gnu and x86_64-linux-gnu.

---
 sysdeps/unix/sysv/linux/mq_notify.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

Comments

Szabolcs Nagy via Libc-alpha June 2, 2021, 1:21 a.m. | #1
On 6/1/21 11:18 PM, Florian Weimer via Libc-alpha wrote:
> __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)").

> 

> Tested on i686-linux-gnu and x86_64-linux-gnu.


Thanks, I missed that in my review.  LGTM.

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


> 

> ---

>   sysdeps/unix/sysv/linux/mq_notify.c | 11 +++++++++--

>   1 file changed, 9 insertions(+), 2 deletions(-)

> 

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

> index f7ddfe5a6c..6f46d29d1d 100644

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

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

> @@ -258,7 +258,14 @@ mq_notify (mqd_t mqdes, const struct sigevent *notification)

>         if (data.attr == NULL)

>   	return -1;

>   

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

> +      int ret = __pthread_attr_copy (data.attr,

> +				     notification->sigev_notify_attributes);

> +      if (ret != 0)

> +	{

> +	  free (data.attr);

> +	  __set_errno (ret);

> +	  return -1;

> +	}

>       }

>   

>     /* Construct the new request.  */

> @@ -271,7 +278,7 @@ mq_notify (mqd_t mqdes, const struct sigevent *notification)

>     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);

>

Patch

diff --git a/sysdeps/unix/sysv/linux/mq_notify.c b/sysdeps/unix/sysv/linux/mq_notify.c
index f7ddfe5a6c..6f46d29d1d 100644
--- a/sysdeps/unix/sysv/linux/mq_notify.c
+++ b/sysdeps/unix/sysv/linux/mq_notify.c
@@ -258,7 +258,14 @@  mq_notify (mqd_t mqdes, const struct sigevent *notification)
       if (data.attr == NULL)
 	return -1;
 
-      __pthread_attr_copy (data.attr, notification->sigev_notify_attributes);
+      int ret = __pthread_attr_copy (data.attr,
+				     notification->sigev_notify_attributes);
+      if (ret != 0)
+	{
+	  free (data.attr);
+	  __set_errno (ret);
+	  return -1;
+	}
     }
 
   /* Construct the new request.  */
@@ -271,7 +278,7 @@  mq_notify (mqd_t mqdes, const struct sigevent *notification)
   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);