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Commit 1e1132ea authored by Mikulas Patocka's avatar Mikulas Patocka Committed by Mike Snitzer
Browse files

dm writecache: fix a crash due to reading past end of dirty_bitmap 

wc->dirty_bitmap_size is in bytes so must multiply it by 8, not by
BITS_PER_LONG, to get number of bitmap_bits.

Fixes crash in find_next_bit() that was reported:
https://bugzilla.kernel.org/show_bug.cgi?id=200819



Reported-by: default avatar <edo.rus@gmail.com>
Fixes: 48debafe ("dm: add writecache target")
Cc: stable@vger.kernel.org # 4.18
Signed-off-by: default avatarMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
parent bc9e9cf0

drivers/md/dm-writecache.c

+1 −1
Original line number Diff line number Diff line
@@ -457,7 +457,7 @@ static void ssd_commit_flushed(struct dm_writecache *wc) 
		COMPLETION_INITIALIZER_ONSTACK(endio.c),

		ATOMIC_INIT(1),

	};

	unsigned bitmap_bits = wc->dirty_bitmap_size * BITS_PER_LONG;

	unsigned bitmap_bits = wc->dirty_bitmap_size * 8;

	unsigned i = 0;



	while (1) {