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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Xu Wen <wen.xu@gatech.edu>,
        Qu Wenruo <wqu@suse.com>, David Sterba <dsterba@suse.com>,
        Sasha Levin <alexander.levin@microsoft.com>
Subject: [PATCH 4.18 133/197] btrfs: Exit gracefully when chunk map cannot be inserted to the tree
Date:   Thu, 13 Sep 2018 15:31:22 +0200
Message-Id: <20180913131846.882504917@linuxfoundation.org>
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4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Qu Wenruo <wqu@suse.com>

[ Upstream commit 64f64f43c89aca1782aa672e0586f6903c5d8979 ]

It's entirely possible that a crafted btrfs image contains overlapping
chunks.

Although we can't detect such problem by tree-checker, it's not a
catastrophic problem, current extent map can already detect such problem
and return -EEXIST.

We just only need to exit gracefully and fail the mount.

Reported-by: Xu Wen <wen.xu@gatech.edu>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=200409
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 fs/btrfs/volumes.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -6563,10 +6563,14 @@ static int read_one_chunk(struct btrfs_f
 	write_lock(&map_tree->map_tree.lock);
 	ret = add_extent_mapping(&map_tree->map_tree, em, 0);
 	write_unlock(&map_tree->map_tree.lock);
-	BUG_ON(ret); /* Tree corruption */
+	if (ret < 0) {
+		btrfs_err(fs_info,
+			  "failed to add chunk map, start=%llu len=%llu: %d",
+			  em->start, em->len, ret);
+	}
 	free_extent_map(em);
 
-	return 0;
+	return ret;
 }
 
 static void fill_device_from_item(struct extent_buffer *leaf,