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From: Nikolay Borisov <nborisov@suse.com>
Date: Mon, 18 Mar 2019 17:45:19 +0200
Subject: btrfs: Fix bound checking in qgroup_trace_new_subtree_blocks
Git-commit: 7ff2c2a1a71e83f74574b8001ea88deb3c166ad7
Patch-mainline: v5.1-rc3
References: git-fixes

If 'cur_level' is 7  then the bound checking at the top of the function
will actually pass. Later on, it's possible to dereference
ds_path->nodes[cur_level+1] which will be an out of bounds.

The correct check will be cur_level >= BTRFS_MAX_LEVEL - 1 .

Fixes-coverty-id: 1440918
Fixes-coverty-id: 1440911
Fixes: ea49f3e73c4b ("btrfs: qgroup: Introduce function to find all new tree blocks of reloc tree")
CC: stable@vger.kernel.org # 4.20+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
---
 fs/btrfs/qgroup.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
index eb680b715dd6..e659d9d61107 100644
--- a/fs/btrfs/qgroup.c
+++ b/fs/btrfs/qgroup.c
@@ -1922,8 +1922,8 @@ static int qgroup_trace_new_subtree_blocks(struct btrfs_trans_handle* trans,
 	int i;
 
 	/* Level sanity check */
-	if (cur_level < 0 || cur_level >= BTRFS_MAX_LEVEL ||
-	    root_level < 0 || root_level >= BTRFS_MAX_LEVEL ||
+	if (cur_level < 0 || cur_level >= BTRFS_MAX_LEVEL - 1 ||
+	    root_level < 0 || root_level >= BTRFS_MAX_LEVEL - 1 ||
 	    root_level < cur_level) {
 		btrfs_err_rl(fs_info,
 			"%s: bad levels, cur_level=%d root_level=%d",