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authorBartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>2016-05-16 09:54:47 -0600
committerJens Axboe <axboe@fb.com>2016-05-16 09:54:47 -0600
commitb3a834b1596ac668df206aa2bb1f191c31f5f5e4 (patch)
treed314fd9bf508256393c7f110e5746834a42ed4c4
parent59fa0224cfea31dde596e29555de94c961b139f9 (diff)
downloadlinux-b3a834b1596ac668df206aa2bb1f191c31f5f5e4.tar.bz2
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>
-rw-r--r--block/blk-mq.c2
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 {