Since the dawn of time bio_check_eod has a check for a non-zero size of
the device. This doesn't really make any sense as we never want to send
I/O to a device that's been set to zero size, or never moved out of that.
I am a bit surprised we haven't caught this for a long time, but the
removal of the extra validation inside of zram caused syzbot to trip
over this issue recently. I've added a Fixes tag for that commit, but
the issue really goes back way before git history.
Fixes: 9fe95babc742 ("zram: remove valid_io_request")
Reported-by: syzbot+b8d61a58b7c7ebd2c8e0@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
block/blk-core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/block/blk-core.c b/block/blk-core.c
index 00c74330fa92c2..1da77e7d628946 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -520,7 +520,7 @@ static inline int bio_check_eod(struct bio *bio)
sector_t maxsector = bdev_nr_sectors(bio->bi_bdev);
unsigned int nr_sectors = bio_sectors(bio);
- if (nr_sectors && maxsector &&
+ if (nr_sectors &&
(nr_sectors > maxsector ||
bio->bi_iter.bi_sector > maxsector - nr_sectors)) {
pr_info_ratelimited("%s: attempt to access beyond end of device\n"
--
2.39.2
