From 7f43d4affb2a254d421ab20b0cf65ac2569909fb Mon Sep 17 00:00:00 2001
From: Qu Wenruo <quwenruo.btrfs@gmx.com>
Date: Wed, 23 Aug 2017 16:57:57 +0900
References: bsc#1102882, bsc#1102896, bsc#1102879, bsc#1102877, bsc#1102875,
 CVE-2018-14613, CVE-2018-14612, CVE-2018-14611, CVE-2018-14610, CVE-2018-14609, 
Patch-mainline: v4.15
Git-commit: 7f43d4affb2a254d421ab20b0cf65ac2569909fb
Subject: [PATCH 2/4] btrfs: Check if item pointer overlaps with the item
 itself

Function check_leaf() checks if any item pointer points outside of the
leaf, but it doesn't check if the pointer overlaps with the item itself.

Normally only the last item may be the victim, but adding such check is
never a bad idea anyway.

Signed-off-by: Qu Wenruo <quwenruo.btrfs@gmx.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
---
 fs/btrfs/disk-io.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 6c97ae1e7288..d1770b3e0385 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -643,6 +643,13 @@ static noinline int check_leaf(struct btrfs_root *root,
 			return -EUCLEAN;
 		}
 
+		/* Also check if the item pointer overlaps with btrfs item. */
+		if (btrfs_item_nr_offset(slot) + sizeof(struct btrfs_item) >
+		    btrfs_item_ptr_offset(leaf, slot)) {
+			CORRUPT("slot overlap with its data", leaf, root, slot);
+			return -EUCLEAN;
+		}
+
 		prev_key.objectid = key.objectid;
 		prev_key.type = key.type;
 		prev_key.offset = key.offset;
-- 
2.18.0