Add another security fix

2 files changed, 61 insertions, 0 deletions

diff --git a/queue-3.16/scsi-libsas-fix-a-race-condition-when-smp-task-timeout.patch b/queue-3.16/scsi-libsas-fix-a-race-condition-when-smp-task-timeout.patch
new file mode 100644
index 00000000..190be44a
--- /dev/null
+++ b/queue-3.16/scsi-libsas-fix-a-race-condition-when-smp-task-timeout.patch
@@ -0,0 +1,60 @@
+From: Jason Yan <yanaijie@huawei.com>
+Date: Tue, 25 Sep 2018 10:56:54 +0800
+Subject: scsi: libsas: fix a race condition when smp task timeout
+
+commit b90cd6f2b905905fb42671009dc0e27c310a16ae upstream.
+
+When the lldd is processing the complete sas task in interrupt and set the
+task stat as SAS_TASK_STATE_DONE, the smp timeout timer is able to be
+triggered at the same time. And smp_task_timedout() will complete the task
+wheter the SAS_TASK_STATE_DONE is set or not. Then the sas task may freed
+before lldd end the interrupt process. Thus a use-after-free will happen.
+
+Fix this by calling the complete() only when SAS_TASK_STATE_DONE is not
+set. And remove the check of the return value of the del_timer(). Once the
+LLDD sets DONE, it must call task->done(), which will call
+smp_task_done()->complete() and the task will be completed and freed
+correctly.
+
+Reported-by: chenxiang <chenxiang66@hisilicon.com>
+Signed-off-by: Jason Yan <yanaijie@huawei.com>
+CC: John Garry <john.garry@huawei.com>
+CC: Johannes Thumshirn <jthumshirn@suse.de>
+CC: Ewan Milne <emilne@redhat.com>
+CC: Christoph Hellwig <hch@lst.de>
+CC: Tomas Henzl <thenzl@redhat.com>
+CC: Dan Williams <dan.j.williams@intel.com>
+CC: Hannes Reinecke <hare@suse.com>
+Reviewed-by: Hannes Reinecke <hare@suse.com>
+Reviewed-by: John Garry <john.garry@huawei.com>
+Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
+Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
+Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
+---
+ drivers/scsi/libsas/sas_expander.c | 9 ++++-----
+ 1 file changed, 4 insertions(+), 5 deletions(-)
+
+--- a/drivers/scsi/libsas/sas_expander.c
++++ b/drivers/scsi/libsas/sas_expander.c
+@@ -47,17 +47,16 @@ static void smp_task_timedout(unsigned l
+ 	unsigned long flags;
+ 
+ 	spin_lock_irqsave(&task->task_state_lock, flags);
+-	if (!(task->task_state_flags & SAS_TASK_STATE_DONE))
++	if (!(task->task_state_flags & SAS_TASK_STATE_DONE)) {
+ 		task->task_state_flags |= SAS_TASK_STATE_ABORTED;
++		complete(&task->slow_task->completion);
++	}
+ 	spin_unlock_irqrestore(&task->task_state_lock, flags);
+-
+-	complete(&task->slow_task->completion);
+ }
+ 
+ static void smp_task_done(struct sas_task *task)
+ {
+-	if (!del_timer(&task->slow_task->timer))
+-		return;
++	del_timer(&task->slow_task->timer);
+ 	complete(&task->slow_task->completion);
+ }
+ 
diff --git a/queue-3.16/series b/queue-3.16/series
index a3dfd056..baff785e 100644
--- a/queue-3.16/series
+++ b/queue-3.16/series
@@ -158,3 +158,4 @@ ipv6-hash-net-ptr-into-fragmentation-bucket-selection.patch
 siphash-add-cryptographically-secure-prf.patch
 inet-switch-ip-id-generator-to-siphash.patch
 netfilter-ctnetlink-don-t-use-conntrack-expect-object-addresses-as.patch
+scsi-libsas-fix-a-race-condition-when-smp-task-timeout.patch