| Message ID | 1465483033-27909-1-git-send-email-kamal@canonical.com |
|---|---|
| State | New |
| Headers | show |
diff --git a/block/blk-mq.c b/block/blk-mq.c index 0990d4c..7d5f8cb 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1488,7 +1488,7 @@ 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 {
This is a note to let you know that I have just added a patch titled blk-mq: fix undefined behaviour in order_to_size() to the linux-4.2.y-queue branch of the 4.2.y-ckt extended stable tree which can be found at: https://git.launchpad.net/~canonical-kernel/linux/+git/linux-stable-ckt/log/?h=linux-4.2.y-queue This patch is scheduled to be released in version 4.2.8-ckt12. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 4.2.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ---8<------------------------------------------------------------ From 8cec5adf9010209ee7e920e961955424be7fb67a Mon Sep 17 00:00:00 2001 From: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> Date: Mon, 16 May 2016 09:54:47 -0600 Subject: blk-mq: fix undefined behaviour in order_to_size() 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: Kamal Mostafa <kamal@canonical.com> --- block/blk-mq.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) -- 2.7.4