From 01239d77b9dd978863d1a75f0d095ab942a1fe66 Mon Sep 17 00:00:00 2001 From: Shan Hai Date: Fri, 10 Aug 2018 17:55:55 -0700 Subject: [PATCH] xfs: fix a null pointer dereference in xfs_bmap_extents_to_btree Fuzzing tool reports a write to null pointer error in the xfs_bmap_extents_to_btree, fix it by bailing out on encountering a null pointer. Signed-off-by: Shan Hai Reviewed-by: Darrick J. Wong Signed-off-by: Darrick J. Wong --- fs/xfs/libxfs/xfs_bmap.c | 24 ++++++++++++++++-------- 1 file changed, 16 insertions(+), 8 deletions(-) diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c index 5648a177e0ac..2760314fdf7f 100644 --- a/fs/xfs/libxfs/xfs_bmap.c +++ b/fs/xfs/libxfs/xfs_bmap.c @@ -712,19 +712,14 @@ xfs_bmap_extents_to_btree( args.wasdel = wasdel; *logflagsp = 0; if ((error = xfs_alloc_vextent(&args))) { - xfs_iroot_realloc(ip, -1, whichfork); ASSERT(ifp->if_broot == NULL); - XFS_IFORK_FMT_SET(ip, whichfork, XFS_DINODE_FMT_EXTENTS); - xfs_btree_del_cursor(cur, XFS_BTREE_ERROR); - return error; + goto err1; } if (WARN_ON_ONCE(args.fsbno == NULLFSBLOCK)) { - xfs_iroot_realloc(ip, -1, whichfork); ASSERT(ifp->if_broot == NULL); - XFS_IFORK_FMT_SET(ip, whichfork, XFS_DINODE_FMT_EXTENTS); - xfs_btree_del_cursor(cur, XFS_BTREE_ERROR); - return -ENOSPC; + error = -ENOSPC; + goto err1; } /* * Allocation can't fail, the space was reserved. @@ -736,6 +731,10 @@ xfs_bmap_extents_to_btree( ip->i_d.di_nblocks++; xfs_trans_mod_dquot_byino(tp, ip, XFS_TRANS_DQ_BCOUNT, 1L); abp = xfs_btree_get_bufl(mp, tp, args.fsbno, 0); + if (!abp) { + error = -ENOSPC; + goto err2; + } /* * Fill in the child block. */ @@ -775,6 +774,15 @@ xfs_bmap_extents_to_btree( *curp = cur; *logflagsp = XFS_ILOG_CORE | xfs_ilog_fbroot(whichfork); return 0; + +err2: + xfs_trans_mod_dquot_byino(tp, ip, XFS_TRANS_DQ_BCOUNT, -1L); +err1: + xfs_iroot_realloc(ip, -1, whichfork); + XFS_IFORK_FMT_SET(ip, whichfork, XFS_DINODE_FMT_EXTENTS); + xfs_btree_del_cursor(cur, XFS_BTREE_ERROR); + + return error; } /* -- 2.45.2