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Commit 2f07fe5d authored by Alexei Filippov's avatar Alexei Filippov Committed by Greg Kroah-Hartman
Browse files

jfs: validate max amount of blocks before allocation. 



[ Upstream commit 0225e10972fa809728b8d4c1bd2772b3ec3fdb57 ]

The lack of checking bmp->db_max_freebud in extBalloc() can lead to
shift out of bounds, so this patch prevents undefined behavior, because
bmp->db_max_freebud == -1 only if there is no free space.

Signed-off-by: default avatarAleksei Filippov <halip0503@gmail.com>
Signed-off-by: default avatarDave Kleikamp <dave.kleikamp@oracle.com>
Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Reported-and-tested-by: default avatar <syzbot+5f088f29593e6b4c8db8@syzkaller.appspotmail.com>
Closes: https://syzkaller.appspot.com/bug?id=01abadbd6ae6a08b1f1987aa61554c6b3ac19ff2


Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 075a4dcd

fs/jfs/jfs_extent.c

+5 −0
Original line number Diff line number Diff line
@@ -521,6 +521,11 @@ extBalloc(struct inode *ip, s64 hint, s64 * nblocks, s64 * blkno) 
	 * blocks in the map. in that case, we'll start off with the

	 * maximum free.

	 */



	/* give up if no space left */

	if (bmp->db_maxfreebud == -1)

		return -ENOSPC;



	max = (s64) 1 << bmp->db_maxfreebud;

	if (*nblocks >= max && *nblocks > nbperpage)

		nb = nblks = (max > nbperpage) ? max : nbperpage;