The max_part may overflow. For example, modprobe brd rd_nr=3 rd_size=102400 max_part=1073741824(2^30)
Expected result NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT ram0 1:0 0 100M 0 disk ram1 1:256 0 100M 0 disk ram2 1:512 0 100M 0 disk Actual result NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT ram0 259:0 0 100M 0 disk ram1 259:1 0 100M 0 disk ram2 259:2 0 100M 0 disk Fix it. Signed-off-by: Lixiaokeng <[email protected]> Signed-off-by: Zhiqiang Liu <[email protected]> --- drivers/block/brd.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff --git a/drivers/block/brd.c b/drivers/block/brd.c index c43a6ab4b1f3..c91831cd5d2a 100644 --- a/drivers/block/brd.c +++ b/drivers/block/brd.c @@ -457,21 +457,19 @@ static void brd_del_one(struct brd_device *brd) static inline void brd_check_and_reset_par(void) { - if (unlikely(!max_part)) + if (unlikely(max_part <= 0)) max_part = 1; /* * make sure 'max_part' can be divided exactly by (1U << MINORBITS), * otherwise, it is possiable to get same dev_t when adding partitions. */ - if ((1U << MINORBITS) % max_part != 0) - max_part = 1UL << fls(max_part); - if (max_part > DISK_MAX_PARTS) { pr_info("brd: max_part can't be larger than %d, reset max_part = %d.\n", DISK_MAX_PARTS, DISK_MAX_PARTS); max_part = DISK_MAX_PARTS; - } + } else if ((1U << MINORBITS) % max_part != 0) + max_part = 1UL << fls(max_part); } static int __init brd_init(void) --
