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| author | Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> | 2016-05-16 09:54:47 -0600 |
|---|---|---|
| committer | Jens Axboe <axboe@fb.com> | 2016-05-16 09:54:47 -0600 |
| commit | b3a834b1596ac668df206aa2bb1f191c31f5f5e4 (patch) | |
| tree | d314fd9bf508256393c7f110e5746834a42ed4c4 /block/blk-mq.c | |
| parent | 59fa0224cfea31dde596e29555de94c961b139f9 (diff) | |
| download | lwn-b3a834b1596ac668df206aa2bb1f191c31f5f5e4.tar.gz lwn-b3a834b1596ac668df206aa2bb1f191c31f5f5e4.zip | |
blk-mq: fix undefined behaviour in order_to_size()
When this_order variable in blk_mq_init_rq_map() becomes zero
the code incorrectly decrements the variable and passes the result
to order_to_size() helper causing undefined behaviour:
UBSAN: Undefined behaviour in block/blk-mq.c:1459:27
shift exponent 4294967295 is too large for 32-bit type 'unsigned int'
CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.6.0-rc6-00072-g33656a1 #22
Fix the code by checking this_order variable for not having the zero
value first.
Reported-by: Meelis Roos <mroos@linux.ee>
Fixes: 320ae51feed5 ("blk-mq: new multi-queue block IO queueing mechanism")
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'block/blk-mq.c')
| -rw-r--r-- | block/blk-mq.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/block/blk-mq.c b/block/blk-mq.c index 0c2ed831c926..7df9c9263b21 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1495,7 +1495,7 @@ static struct blk_mq_tags *blk_mq_init_rq_map(struct blk_mq_tag_set *set, int to_do; void *p; - while (left < order_to_size(this_order - 1) && this_order) + while (this_order && left < order_to_size(this_order - 1)) this_order--; do { |