From cb335f88eb35af712d1f4171642d0487f7bb2e7e Mon Sep 17 00:00:00 2001 From: Nicolas Schichan Date: Wed, 15 Jan 2014 16:58:52 +0100 Subject: md: check command validity early in md_ioctl(). Verify that the cmd parameter passed to md_ioctl() is valid before doing anything. This fixes mddev->hold_active being set to 0 when an invalid ioctl command is passed to md_ioctl() before the array has been configured. Clearing mddev->hold_active in that case can lead to a livelock situation when an invalid ioctl number is given to md_ioctl() by a process when the mddev is currently being opened by another process: Process 1 Process 2 --------- --------- md_alloc() mddev_find() -> returns a new mddev with hold_active == UNTIL_IOCTL add_disk() -> sends KOBJ_ADD uevent (sees KOBJ_ADD uevent for device) md_open() md_ioctl(INVALID_IOCTL) -> returns ENODEV and clears mddev->hold_active md_release() md_put() -> deletes the mddev as hold_active is 0 md_open() mddev_find() -> returns a newly allocated mddev with mddev->gendisk == NULL -> returns with ERESTARTSYS (kernel restarts the open syscall) Signed-off-by: Nicolas Schichan Signed-off-by: NeilBrown --- drivers/md/md.c | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) (limited to 'drivers/md') diff --git a/drivers/md/md.c b/drivers/md/md.c index a20b7806de7a..b890d3fb0e02 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -6356,6 +6356,32 @@ static int md_getgeo(struct block_device *bdev, struct hd_geometry *geo) return 0; } +static inline bool md_ioctl_valid(unsigned int cmd) +{ + switch (cmd) { + case ADD_NEW_DISK: + case BLKROSET: + case GET_ARRAY_INFO: + case GET_BITMAP_FILE: + case GET_DISK_INFO: + case HOT_ADD_DISK: + case HOT_REMOVE_DISK: + case PRINT_RAID_DEBUG: + case RAID_AUTORUN: + case RAID_VERSION: + case RESTART_ARRAY_RW: + case RUN_ARRAY: + case SET_ARRAY_INFO: + case SET_BITMAP_FILE: + case SET_DISK_FAULTY: + case STOP_ARRAY: + case STOP_ARRAY_RO: + return true; + default: + return false; + } +} + static int md_ioctl(struct block_device *bdev, fmode_t mode, unsigned int cmd, unsigned long arg) { @@ -6364,6 +6390,9 @@ static int md_ioctl(struct block_device *bdev, fmode_t mode, struct mddev *mddev = NULL; int ro; + if (!md_ioctl_valid(cmd)) + return -ENOTTY; + switch (cmd) { case RAID_VERSION: case GET_ARRAY_INFO: -- cgit v1.2.3