3.6-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Chris Ball <c...@laptop.org>

commit 14efd957209461bbdf285bf0d67e931955d04a4c upstream.

Commit 473b095a72a9 ("mmc: sdhci: fix incorrect command used in tuning")
introduced a NULL dereference at resume-time if an SD 3.0 host controller
raises the SDHCI_NEEDS_TUNING flag while no card is inserted.  Seen on an
OLPC XO-4 with sdhci-pxav3, but presumably affects other controllers too.

Signed-off-by: Chris Ball <c...@laptop.org>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 drivers/mmc/host/sdhci.c |   21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -1307,16 +1307,19 @@ static void sdhci_request(struct mmc_hos
                 */
                if ((host->flags & SDHCI_NEEDS_RETUNING) &&
                    !(present_state & (SDHCI_DOING_WRITE | SDHCI_DOING_READ))) {
-                       /* eMMC uses cmd21 while sd and sdio use cmd19 */
-                       tuning_opcode = mmc->card->type == MMC_TYPE_MMC ?
-                               MMC_SEND_TUNING_BLOCK_HS200 :
-                               MMC_SEND_TUNING_BLOCK;
-                       spin_unlock_irqrestore(&host->lock, flags);
-                       sdhci_execute_tuning(mmc, tuning_opcode);
-                       spin_lock_irqsave(&host->lock, flags);
+                       if (mmc->card) {
+                               /* eMMC uses cmd21 but sd and sdio use cmd19 */
+                               tuning_opcode =
+                                       mmc->card->type == MMC_TYPE_MMC ?
+                                       MMC_SEND_TUNING_BLOCK_HS200 :
+                                       MMC_SEND_TUNING_BLOCK;
+                               spin_unlock_irqrestore(&host->lock, flags);
+                               sdhci_execute_tuning(mmc, tuning_opcode);
+                               spin_lock_irqsave(&host->lock, flags);
 
-                       /* Restore original mmc_request structure */
-                       host->mrq = mrq;
+                               /* Restore original mmc_request structure */
+                               host->mrq = mrq;
+                       }
                }
 
                if (mrq->sbc && !(host->flags & SDHCI_AUTO_CMD23))


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