Messages in this thread | | | Date | Sat, 14 May 2016 12:05:56 +0300 (EEST) | From | Meelis Roos <> | Subject | Re: UBSAN: Undefined behaviour in block/blk-mq.c:1459:27 with pata_amd |
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> Does the patch below help?
Yes, the warning is gone and I see not other errors.
There is nothing attached to pata_amd so I do not know if it works too.
> > From: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> > Subject: [PATCH] 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> > --- > block/blk-mq.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/block/blk-mq.c b/block/blk-mq.c > index 0c2ed83..7df9c92 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 { >
-- Meelis Roos (mroos@linux.ee)
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