Qu Wenruo
2014-Sep-18 04:01 UTC
[PATCH 1/2] btrfs: Add more check before read_extent_buffer() to avoid read overflow.
Before this patch, when replay_one_extent() find an existing file extent item, btrfs will call read_extent_buffer() to read out the file extent. However it lacks enough check, and may read out the inline file extent using the wrong size(currently it always uses sizeof(btrfs_file_extent_item)) If a inline file extent's size is smaller than normal file extent size(53 bytes) and unfortunately the inline file extent lies at the end of a full leaf, WARN_ON in read_extent_buffer() will be triggered. This patch will check the file extent type before calling read_extent_buffer(), since the if the logged one and the existing one are all preallocated/regular file extent item, their size must be sizeof(struct btrfs_file_extent_item) and will avoid the read overflow. Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com> --- fs/btrfs/tree-log.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c index 7e0e6e3..1ea2b10 100644 --- a/fs/btrfs/tree-log.c +++ b/fs/btrfs/tree-log.c @@ -620,6 +620,8 @@ static noinline int replay_one_extent(struct btrfs_trans_handle *trans, existing = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_file_extent_item); + if (btrfs_file_extent_type(leaf, existing) != found_type) + goto no_compare; read_extent_buffer(eb, &cmp1, (unsigned long)item, sizeof(cmp1)); read_extent_buffer(leaf, &cmp2, (unsigned long)existing, @@ -634,6 +636,7 @@ static noinline int replay_one_extent(struct btrfs_trans_handle *trans, goto out; } } +no_compare: btrfs_release_path(path); /* drop any overlapping extents */ -- 2.1.0 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html