From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ken Xue Subject: [PATCH 2/2] SCSI: Fix NULL pointer dereference in runtime PM Date: Tue, 1 Dec 2015 14:45:46 +0800 Message-ID: <1448952346.3603.18.camel@kxue-X58A-UD3R> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: Sender: stable-owner@vger.kernel.org To: linux-scsi@vger.kernel.org, linux-block@vger.kernel.org, stable@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Xiangliang.Yu@amd.com, stern@rowland.harvard.edu, JBottomley@Odin.com, SPG_Linux_Kernel@amd.com, axboe@kernel.dk, michael.terry@canonical.com List-Id: linux-scsi@vger.kernel.org The routines in scsi_pm.c assume that if a runtime-PM callback is invoked for a SCSI device, it can only mean that the device's driver has asked the block layer to handle the runtime power management (by calling blk_pm_runtime_init(), which among other things sets q->dev). However, this assumption turns out to be wrong for things like the ses driver. Normally ses devices are not allowed to do runtime PM, but userspace can override this setting. If this happens, the kernel gets a NULL pointer dereference when blk_post_runtime_resume() tries to use the uninitialized q->dev pointer. This patch fixes the problem by checking q->dev in block layer before handle runtime PM. Since ses doesn't define any PM callbacks and call blk_pm_runtime_init(), the crash won't occur. This fixes Bugzilla #101371. https://bugzilla.kernel.org/show_bug.cgi?id=101371 More discussion can be found from below link. http://marc.info/?l=linux-scsi&m=144163730531875&w=2 Signed-off-by: Ken Xue Acked-by: Alan Stern Cc: Xiangliang Yu Cc: James E.J. Bottomley Cc: Jens Axboe Cc: Michael Terry Cc: stable@vger.kernel.org --- block/blk-core.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/block/blk-core.c b/block/blk-core.c index 60912e9..a07ab18 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -3280,6 +3280,9 @@ int blk_pre_runtime_suspend(struct request_queue *q) { int ret = 0; + if (!q->dev) + return ret; + spin_lock_irq(q->queue_lock); if (q->nr_pending) { ret = -EBUSY; @@ -3307,6 +3310,9 @@ EXPORT_SYMBOL(blk_pre_runtime_suspend); */ void blk_post_runtime_suspend(struct request_queue *q, int err) { + if (!q->dev) + return; + spin_lock_irq(q->queue_lock); if (!err) { q->rpm_status = RPM_SUSPENDED; @@ -3331,6 +3337,9 @@ EXPORT_SYMBOL(blk_post_runtime_suspend); */ void blk_pre_runtime_resume(struct request_queue *q) { + if (!q->dev) + return; + spin_lock_irq(q->queue_lock); q->rpm_status = RPM_RESUMING; spin_unlock_irq(q->queue_lock); @@ -3353,6 +3362,9 @@ EXPORT_SYMBOL(blk_pre_runtime_resume); */ void blk_post_runtime_resume(struct request_queue *q, int err) { + if (!q->dev) + return; + spin_lock_irq(q->queue_lock); if (!err) { q->rpm_status = RPM_ACTIVE; -- 1.9.1