66 lines
2.5 KiB
Diff
66 lines
2.5 KiB
Diff
From b90cd6f2b905905fb42671009dc0e27c310a16ae Mon Sep 17 00:00:00 2001
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From: Jason Yan <yanaijie@huawei.com>
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Date: Tue, 25 Sep 2018 10:56:54 +0800
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Subject: scsi: libsas: fix a race condition when smp task timeout
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Origin: https://git.kernel.org/linus/b90cd6f2b905905fb42671009dc0e27c310a16ae
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Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2018-20836
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When the lldd is processing the complete sas task in interrupt and set the
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task stat as SAS_TASK_STATE_DONE, the smp timeout timer is able to be
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triggered at the same time. And smp_task_timedout() will complete the task
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wheter the SAS_TASK_STATE_DONE is set or not. Then the sas task may freed
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before lldd end the interrupt process. Thus a use-after-free will happen.
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Fix this by calling the complete() only when SAS_TASK_STATE_DONE is not
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set. And remove the check of the return value of the del_timer(). Once the
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LLDD sets DONE, it must call task->done(), which will call
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smp_task_done()->complete() and the task will be completed and freed
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correctly.
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Reported-by: chenxiang <chenxiang66@hisilicon.com>
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Signed-off-by: Jason Yan <yanaijie@huawei.com>
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CC: John Garry <john.garry@huawei.com>
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CC: Johannes Thumshirn <jthumshirn@suse.de>
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CC: Ewan Milne <emilne@redhat.com>
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CC: Christoph Hellwig <hch@lst.de>
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CC: Tomas Henzl <thenzl@redhat.com>
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CC: Dan Williams <dan.j.williams@intel.com>
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CC: Hannes Reinecke <hare@suse.com>
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Reviewed-by: Hannes Reinecke <hare@suse.com>
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Reviewed-by: John Garry <john.garry@huawei.com>
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Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
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Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
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---
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drivers/scsi/libsas/sas_expander.c | 9 ++++-----
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1 file changed, 4 insertions(+), 5 deletions(-)
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diff --git a/drivers/scsi/libsas/sas_expander.c b/drivers/scsi/libsas/sas_expander.c
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index 52222940d398..0d1f72752ca2 100644
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--- a/drivers/scsi/libsas/sas_expander.c
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+++ b/drivers/scsi/libsas/sas_expander.c
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@@ -48,17 +48,16 @@ static void smp_task_timedout(struct timer_list *t)
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unsigned long flags;
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spin_lock_irqsave(&task->task_state_lock, flags);
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- if (!(task->task_state_flags & SAS_TASK_STATE_DONE))
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+ if (!(task->task_state_flags & SAS_TASK_STATE_DONE)) {
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task->task_state_flags |= SAS_TASK_STATE_ABORTED;
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+ complete(&task->slow_task->completion);
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+ }
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spin_unlock_irqrestore(&task->task_state_lock, flags);
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-
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- complete(&task->slow_task->completion);
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}
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static void smp_task_done(struct sas_task *task)
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{
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- if (!del_timer(&task->slow_task->timer))
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- return;
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+ del_timer(&task->slow_task->timer);
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complete(&task->slow_task->completion);
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}
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--
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cgit 1.2-0.3.lf.el7
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