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authorKen Xue <ken.xue@amd.com>2015-12-01 14:45:46 +0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2016-02-25 11:58:53 -0800
commit10e3ac0ebf1a3b7b178a7186bfb967d8fad61b2c (patch)
treeaecd4cd1766c16f76308af0b242b1954ed94cc17
parent604e034dfb2f5bb8b840e1ab7e0c182cfd4fd004 (diff)
downloadlwn-10e3ac0ebf1a3b7b178a7186bfb967d8fad61b2c.tar.gz
lwn-10e3ac0ebf1a3b7b178a7186bfb967d8fad61b2c.zip
SCSI: Fix NULL pointer dereference in runtime PM
commit 4fd41a8552afc01054d9d9fc7f1a63c324867d27 upstream. 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 <Ken.Xue@amd.com> Acked-by: Alan Stern <stern@rowland.harvard.edu> Cc: Xiangliang Yu <Xiangliang.Yu@amd.com> Cc: James E.J. Bottomley <JBottomley@odin.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Michael Terry <Michael.terry@canonical.com> Signed-off-by: Jens Axboe <axboe@fb.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--block/blk-core.c12
1 files changed, 12 insertions, 0 deletions
diff --git a/block/blk-core.c b/block/blk-core.c
index e45b321cf6a0..46be0cddf819 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -3164,6 +3164,9 @@ 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;
@@ -3191,6 +3194,9 @@ 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;
@@ -3215,6 +3221,9 @@ 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);
@@ -3237,6 +3246,9 @@ 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;