| Message ID | 1499245637-28870-2-git-send-email-geert@linux-m68k.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c index 9472e89af3efa37e..b236d345d53291f0 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;
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 <geert@linux-m68k.org> --- Should mmc_blk_ioctl_multi_cmd() return -EINVAL instead for this case? That would change behavior as seen from userspace, though. Feel free to fold in the previous patch if deemed appropriate. --- drivers/mmc/core/block.c | 3 +++ 1 file changed, 3 insertions(+)