linux-kernel - [PATCH 5.1 327/371] block: Fix potential overflow in blk_report

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Message-Id: <20190724191748.443843713@linuxfoundation.org>
Date:   Wed, 24 Jul 2019 21:21:19 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Damien Le Moal <damien.lemoal@....com>,
        Jens Axboe <axboe@...nel.dk>
Subject: [PATCH 5.1 327/371] block: Fix potential overflow in blk_report_zones()

From: Damien Le Moal <damien.lemoal@....com>

commit 113ab72ed4794c193509a97d7c6d32a6886e1682 upstream.

For large values of the number of zones reported and/or large zone
sizes, the sector increment calculated with

blk_queue_zone_sectors(q) * n

in blk_report_zones() loop can overflow the unsigned int type used for
the calculation as both "n" and blk_queue_zone_sectors() value are
unsigned int. E.g. for a device with 256 MB zones (524288 sectors),
overflow happens with 8192 or more zones reported.

Changing the return type of blk_queue_zone_sectors() to sector_t, fixes
this problem and avoids overflow problem for all other callers of this
helper too. The same change is also applied to the bdev_zone_sectors()
helper.

Fixes: e76239a3748c ("block: add a report_zones method")
Cc: stable@...r.kernel.org
Signed-off-by: Damien Le Moal <damien.lemoal@....com>
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 block/blk-zoned.c      |    2 +-
 include/linux/blkdev.h |    4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

--- a/block/blk-zoned.c
+++ b/block/blk-zoned.c
@@ -69,7 +69,7 @@ EXPORT_SYMBOL_GPL(__blk_req_zone_write_u
 static inline unsigned int __blkdev_nr_zones(struct request_queue *q,
 					     sector_t nr_sectors)
 {
-	unsigned long zone_sectors = blk_queue_zone_sectors(q);
+	sector_t zone_sectors = blk_queue_zone_sectors(q);
 
 	return (nr_sectors + zone_sectors - 1) >> ilog2(zone_sectors);
 }
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -662,7 +662,7 @@ static inline bool blk_queue_is_zoned(st
 	}
 }
 
-static inline unsigned int blk_queue_zone_sectors(struct request_queue *q)
+static inline sector_t blk_queue_zone_sectors(struct request_queue *q)
 {
 	return blk_queue_is_zoned(q) ? q->limits.chunk_sectors : 0;
 }
@@ -1400,7 +1400,7 @@ static inline bool bdev_is_zoned(struct
 	return false;
 }
 
-static inline unsigned int bdev_zone_sectors(struct block_device *bdev)
+static inline sector_t bdev_zone_sectors(struct block_device *bdev)
 {
 	struct request_queue *q = bdev_get_queue(bdev);