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@xxxxxxxxxxxxxx>
---
v2, as suggested by Arnd:
- Move the assignment after "case MMC_DRV_OP_IOCTL", to keep getting
compile-time checks on the state of the 'ret' variable,
- Initialize ret to zero instead of -EINVAL.
---
drivers/mmc/core/block.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
index 0cfac2d391073922..4920ea1ece38a9b6 100644
--- 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;
--
2.7.4
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