Commit 0225e109 authored by Alexei Filippov's avatar Alexei Filippov Committed by Dave Kleikamp
Browse files

jfs: validate max amount of blocks before allocation. 



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
parent 87098a0d

fs/jfs/jfs_extent.c

+5 −0
Original line number Diff line number Diff line
@@ -311,6 +311,11 @@ 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;