mmc: block: Initialize ret in mmc_blk_issue_drv_op() for MMC_DRV_OP_IOCTL

With gcc 4.1.2:

    drivers/mmc/core/block.c: In function ‘mmc_blk_issue_drv_op’:
    drivers/mmc/core/block.c:1178: warning: ‘ret’ may be used uninitialized in this function

Indeed, for MMC_DRV_OP_IOCTL, if mq_rq->ioc_count is zero, an
uninitialized value will be stored in mq_rq->drv_op_result and passed to
blk_end_request_all().

Can mq_rq->ioc_count be zero?
  - mmc_blk_ioctl_cmd() sets ioc_count to 1, so this is safe,
  - mmc_blk_ioctl_multi_cmd() obtains ioc_count from user space in
    response to the MMC_IOC_MULTI_CMD ioctl, and does allow zero.

Initialize ret to zero to fix this for current and future callers.

Fixes: 0493f6fe5bdee8ac ("mmc: block: Move boot partition locking into a driver op")
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
index 0cfac2d3910739228b18cca0ed5f4f11fa51608b..4920ea1ece38a9b6b71c0d724290726fefcf1acf 100644 (file)
--- a/drivers/mmc/core/block.c
+++ b/drivers/mmc/core/block.c
@@ -1182,7 +1182,7 @@ static void mmc_blk_issue_drv_op(struct mmc_queue *mq, struct request *req)
 
        switch (mq_rq->drv_op) {
        case MMC_DRV_OP_IOCTL:
-               for (i = 0; i < mq_rq->ioc_count; i++) {
+               for (i = 0, ret = 0; i < mq_rq->ioc_count; i++) {
                        ret = __mmc_blk_ioctl_cmd(card, md, mq_rq->idata[i]);
                        if (ret)
                                break;