Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 4.4 245/312] blk-mq: fix undefined behaviour in order_to_size() | Date | Fri, 8 May 2020 14:33:56 +0200 |
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From: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
commit b3a834b1596ac668df206aa2bb1f191c31f5f5e4 upstream.
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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- block/blk-mq.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1491,7 +1491,7 @@ static struct blk_mq_tags *blk_mq_init_r 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 {
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