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Subject[34-longterm 109/196] mmc: sdhci: Check mrq != NULL in sdhci_tasklet_finish
Date
From: Chris Ball <cjb@laptop.org>

-------------------
This is a commit scheduled for the next v2.6.34 longterm release.
If you see a problem with using this for longterm, please comment.
-------------------

commit 0c9c99a765321104cc5f9c97f949382a9ba4927e upstream.

It seems that under certain circumstances the sdhci_tasklet_finish()
call can be entered with mrq set to NULL, causing the system to crash
with a NULL pointer de-reference.

Seen on S3C6410 system. Based on a patch by Dimitris Papastamos.

Reported-by: Dimitris Papastamos <dp@opensource.wolfsonmicro.com>
Signed-off-by: Chris Ball <cjb@laptop.org>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
---
drivers/mmc/host/sdhci.c | 7 +++++++
1 file changed, 7 insertions(+)

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 6441e22..be410d7 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -1268,6 +1268,13 @@ static void sdhci_tasklet_finish(unsigned long param)

host = (struct sdhci_host*)param;

+ /*
+ * If this tasklet gets rescheduled while running, it will
+ * be run again afterwards but without any active request.
+ */
+ if (!host->mrq)
+ return;
+
spin_lock_irqsave(&host->lock, flags);

del_timer(&host->timer);
--
1.7.9.3


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