On 09/11/2017 08:58 AM, Mike Snitzer wrote: > On Mon, Aug 14 2017 at 8:01pm -0400, > Mikulas Patocka <mpatocka@xxxxxxxxxx> wrote: > >> >> >> On Mon, 14 Aug 2017, Damien Le Moal wrote: >> >>> On Sun, 2017-08-13 at 22:47 -0400, Mikulas Patocka wrote: >>>> >>>> On Wed, 9 Aug 2017, hch@xxxxxx wrote: >>>> >>>>> Does commit 615d22a51c04856efe62af6e1d5b450aaf5cc2c0 >>>>> "block: Fix __blkdev_issue_zeroout loop" fix the issue for you? >>>>> >>>>> -- >>>>> dm-devel mailing list >>>>> dm-devel@xxxxxxxxxx >>>>> https://www.redhat.com/mailman/listinfo/dm-devel >>>> >>>> I think that patch is incorrect. sector_t may be a 32-bit type and >>>> nr_sects << 9 may overflow. >>>> >>>> static unsigned int __blkdev_sectors_to_bio_pages(sector_t nr_sects) >>>> { >>>> sector_t bytes = (nr_sects << 9) + PAGE_SIZE - 1; >>>> >>>> return min(bytes >> PAGE_SHIFT, (sector_t)BIO_MAX_PAGES); >>>> } >>>> >>>> Mikulas >>> >>> Mikulas, >>> >>> Does the follwing patch fix the problem ? >>> >>> From 947b3cf41e759b2b23f684e215e651d0c8037f88 Mon Sep 17 00:00:00 2001 >>> From: Damien Le Moal <damien.lemoal@xxxxxxx> >>> Date: Mon, 14 Aug 2017 13:01:16 +0900 >>> Subject: [PATCH] block: Fix __blkdev_sectors_to_bio_pages() >>> >>> On 32bit systems where sector_t is a 32bits type, the calculation of >>> bytes may overflow. Use the u64 type for the local calculation to avoid >>> overflows. >>> >>> Signed-off-by: Damien Le Moal <damien.lemoal@xxxxxxx> >>> --- >>> block/blk-lib.c | 4 ++-- >>> 1 file changed, 2 insertions(+), 2 deletions(-) >>> >>> diff --git a/block/blk-lib.c b/block/blk-lib.c >>> index 3fe0aec90597..ccf22dba21f0 100644 >>> --- a/block/blk-lib.c >>> +++ b/block/blk-lib.c >>> @@ -269,9 +269,9 @@ static int __blkdev_issue_write_zeroes(struct block_device >>> *bdev, >>> */ >>> static unsigned int __blkdev_sectors_to_bio_pages(sector_t nr_sects) >>> { >>> - sector_t bytes = (nr_sects << 9) + PAGE_SIZE - 1; >>> + u64 bytes = ((u64)nr_sects << 9) + PAGE_SIZE - 1; >>> >>> - return min(bytes >> PAGE_SHIFT, (sector_t)BIO_MAX_PAGES); >>> + return min(bytes >> PAGE_SHIFT, (u64)BIO_MAX_PAGES); >>> } >>> >> >> It's OK, but it is not needed to use 64-bit arithmetic here if all we need >> is to shift the value right. Here I submit a simplified patch, using the >> macro DIV_ROUND_UP_SECTOR_T (the macro gets optimized to just an addition >> and right shift). >> >> >> >> From: Mikulas Patocka <mpatocka@xxxxxxxxxx> >> >> Fix possible integer overflow in __blkdev_sectors_to_bio_pages if sector_t >> is 32-bit. >> >> Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx> >> Fixes: 615d22a51c04 ("block: Fix __blkdev_issue_zeroout loop") >> >> --- >> block/blk-lib.c | 4 ++-- >> 1 file changed, 2 insertions(+), 2 deletions(-) >> >> Index: linux-2.6/block/blk-lib.c >> =================================================================== >> --- linux-2.6.orig/block/blk-lib.c >> +++ linux-2.6/block/blk-lib.c >> @@ -269,9 +269,9 @@ static int __blkdev_issue_write_zeroes(s >> */ >> static unsigned int __blkdev_sectors_to_bio_pages(sector_t nr_sects) >> { >> - sector_t bytes = (nr_sects << 9) + PAGE_SIZE - 1; >> + sector_t pages = DIV_ROUND_UP_SECTOR_T(nr_sects, PAGE_SIZE / 512); >> >> - return min(bytes >> PAGE_SHIFT, (sector_t)BIO_MAX_PAGES); >> + return min(pages, (sector_t)BIO_MAX_PAGES); >> } >> >> /** >> > > Jens can you pick this up? Yep added, thanks. -- Jens Axboe
