Commit db52d09e authored Nov 28, 2014 by Eric Sandeen Committed by Dave Chinner Nov 28, 2014

xfs: catch invalid negative blknos in _xfs_buf_find()



Here blkno is a daddr_t, which is a __s64; it's possible to hold
a value which is negative, and thus pass the (blkno >= eofs)
test.  Then we try to do a xfs_perag_get() for a ridiculous
agno via xfs_daddr_to_agno(), and bad things happen when that
fails, and returns a null pag which is dereferenced shortly
thereafter.

Found via a user-supplied fuzzed image...

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

parent 91ee575f

fs/xfs/xfs_buf.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -461,7 +461,7 @@ _xfs_buf_find(
		* have to check that the buffer falls within the filesystem bounds.
		*/
		eofs = XFS_FSB_TO_BB(btp->bt_mount, btp->bt_mount->m_sb.sb_dblocks);
		if (blkno >= eofs) {
		if (blkno < 0 \|\| blkno >= eofs) {
		/*
		* XXX (dgc): we should really be returning -EFSCORRUPTED here,
		* but none of the higher level infrastructure supports