From db52d09ecbf85c54e263a9d1ebfb615a9b2b3ba6 Mon Sep 17 00:00:00 2001 From: Eric Sandeen Date: Fri, 28 Nov 2014 14:03:55 +1100 Subject: [PATCH] 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 Reviewed-by: Mark Tinguely Signed-off-by: Dave Chinner --- fs/xfs/xfs_buf.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c index c06d790..d083889 100644 --- a/fs/xfs/xfs_buf.c +++ b/fs/xfs/xfs_buf.c @@ -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 -- 2.7.4