From: Chris Ball <cjb@laptop.org>
Date: Wed, 27 Apr 2011 21:35:31 +0000 (-0400)
Subject: mmc: sdhci: Check mrq != NULL in sdhci_tasklet_finish
X-Git-Tag: v2.6.34.11~89
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=e8085b98def971e5f8e3a9178b71cdef47aa9cda;p=thirdparty%2Fkernel%2Fstable.git

mmc: sdhci: Check mrq != NULL in sdhci_tasklet_finish

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>
---

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 6441e2234bfb0..be410d7d8273c 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);