From aab2ee03912be6e12bb5f4810be0b80a82168d3e Mon Sep 17 00:00:00 2001 From: Geert Uytterhoeven Date: Wed, 5 Jul 2017 17:09:42 +0200 Subject: [PATCH] mmc: block: Let MMC_IOC_MULTI_CMD return zero again for zero entries MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit With gcc 4.1.2: drivers/mmc/core/block.c: In function ‘mmc_blk_ioctl_cmd_issue’: drivers/mmc/core/block.c:630: warning: ‘ioc_err’ may be used uninitialized in this function Indeed, 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. To avoid returning an uninitialized value, and as it is pointless to do all this work when the MMC_IOC_MULTI_CMD ioctl is used with zero entries, check for this early in mmc_blk_ioctl_multi_cmd(), and return zero, like was returned before. Fixes: 3ecd8cf23f88d5df ("mmc: block: move multi-ioctl() to use block layer") Signed-off-by: Geert Uytterhoeven Signed-off-by: Ulf Hansson --- drivers/mmc/core/block.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c index 4920ea1ece38..e0363223996e 100644 --- a/drivers/mmc/core/block.c +++ b/drivers/mmc/core/block.c @@ -637,6 +637,9 @@ static int mmc_blk_ioctl_multi_cmd(struct block_device *bdev, sizeof(num_of_cmds))) return -EFAULT; + if (!num_of_cmds) + return 0; + if (num_of_cmds > MMC_IOC_MAX_CMDS) return -EINVAL; -- 2.20.1