We should return -EINVAL if cmd is not MMC_IOC_CMD or MMC_IOC_MULTI_CMD, otherwise blkdev_roset will return -EPERM. Android-adb calls make_block_device_writable with ioctl(BLKROSET), which will return error, make remount failed: remount of /system failed; couldn't make block device writable: Operation not permitted openat(AT_FDCWD, "/dev/block/platform/ff420000.dwmmc/by-name/system", O_RDONLY) = 3 ioctl(3, BLKROSET, 0) = -1 EPERM (Operation not permitted) Fixes: a5f5774c55a2 ("mmc: block: Add new ioctl to send multi commands") Cc: <stable@xxxxxxxxxxxxxxx> # 4.4.x Signed-off-by: Shawn Lin <shawn.lin@xxxxxxxxxxxxxx> --- drivers/mmc/card/block.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c index 47bc87d..170f099 100644 --- a/drivers/mmc/card/block.c +++ b/drivers/mmc/card/block.c @@ -688,6 +688,9 @@ cmd_err: static int mmc_blk_ioctl(struct block_device *bdev, fmode_t mode, unsigned int cmd, unsigned long arg) { + if (cmd != MMC_IOC_CMD && cmd != MMC_IOC_MULTI_CMD) + return -EINVAL; + /* * The caller must have CAP_SYS_RAWIO, and must be calling this on the * whole block device, not on a partition. This prevents overspray -- 2.3.7 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html