From 36c8f6bd9efc934f847e0b0bf17446ec25288396 Mon Sep 17 00:00:00 2001
From: Shan Hai <shan.hai@oracle.com>
Date: Fri, 10 Aug 2018 17:55:55 -0700
Subject: [PATCH 1/3] xfs: fix a null pointer dereference in
xfs_bmap_extents_to_btree
Git-commit: 01239d77b9dd978863d1a75f0d095ab942a1fe66
Patch-mainline: v4.19-rc1
References: bsc#1099999, CVE-2018-13095
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 <shan.hai@oracle.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Acked-by: Nikolay Borisov <nborisov@suse.com>
---
fs/xfs/libxfs/xfs_bmap.c | 24 ++++++++++++++++--------
1 file changed, 16 insertions(+), 8 deletions(-)
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -773,19 +773,14 @@ 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.
@@ -797,6 +792,10 @@ 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.
*/
@@ -839,6 +838,15 @@ 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;
}
/*