Patch "target/user: Fix use-after-free of tcmu_cmds if they are expired" has been added to the 4.9-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    target/user: Fix use-after-free of tcmu_cmds if they are expired

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     target-user-fix-use-after-free-of-tcmu_cmds-if-they-are-expired.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From d0905ca757bc40bd1ebc261a448a521b064777d7 Mon Sep 17 00:00:00 2001
From: Andy Grover <agrover@redhat.com>
Date: Mon, 21 Nov 2016 16:35:30 -0800
Subject: target/user: Fix use-after-free of tcmu_cmds if they are expired

From: Andy Grover <agrover@redhat.com>

commit d0905ca757bc40bd1ebc261a448a521b064777d7 upstream.

Don't free the cmd in tcmu_check_expired_cmd, it's still referenced by
an entry in our cmd_id->cmd idr. If userspace ever resumes processing,
tcmu_handle_completions() will use the now-invalid cmd pointer.

Instead, don't free cmd. It will be freed by tcmu_handle_completion() if
userspace ever recovers, or tcmu_free_device if not.

Reported-by: Bryant G Ly <bgly@us.ibm.com>
Tested-by: Bryant G Ly <bgly@us.ibm.com>
Signed-off-by: Andy Grover <agrover@redhat.com>
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/target/target_core_user.c |    2 --
 1 file changed, 2 deletions(-)

--- a/drivers/target/target_core_user.c
+++ b/drivers/target/target_core_user.c
@@ -685,8 +685,6 @@ static int tcmu_check_expired_cmd(int id
 	target_complete_cmd(cmd->se_cmd, SAM_STAT_CHECK_CONDITION);
 	cmd->se_cmd = NULL;
 
-	kmem_cache_free(tcmu_cmd_cache, cmd);
-
 	return 0;
 }
 


Patches currently in stable-queue which might be from agrover@redhat.com are

queue-4.9/target-user-fix-use-after-free-of-tcmu_cmds-if-they-are-expired.patch