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btrfs: Check that each block group has corresponding chunk at mount time

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A crafted btrfs image with incorrect chunk<->block group mapping will
trigger a lot of unexpected things as the mapping is essential.

Although the problem can be caught by block group item checker
added in "btrfs: tree-checker: Verify block_group_item", it's still not
sufficient.  A sufficiently valid block group item can pass the check
added by the mentioned patch but could fail to match the existing chunk.

This patch will add extra block group -> chunk mapping check, to ensure
we have a completely matching (start, len, flags) chunk for each block
group at mount time.

Here we reuse the original helper find_first_block_group(), which is
already doing the basic bg -> chunk checks, adding further checks of the
start/len and type flags.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=199837
Reported-by: Xu Wen <wen.xu@gatech.edu>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Su Yue <suy.fnst@cn.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Qu Wenruo 2018-08-01 10:37:16 +08:00 committed by David Sterba
parent 22d3151c2c
commit 514c7dca85
1 changed files with 27 additions and 1 deletions
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28
fs/btrfs/extent-tree.c
View file

@ -9532,6 +9532,8 @@ static int find_first_block_group(struct btrfs_fs_info *fs_info,
int ret = 0;
struct btrfs_key found_key;
struct extent_buffer *leaf;
struct btrfs_block_group_item bg;
u64 flags;
int slot;
ret = btrfs_search_slot(NULL, root, key, path, 0, 0);
@ -9566,8 +9568,32 @@ static int find_first_block_group(struct btrfs_fs_info *fs_info,
"logical %llu len %llu found bg but no related chunk",
found_key.objectid, found_key.offset);
ret = -ENOENT;
} else if (em->start != found_key.objectid ||
em->len != found_key.offset) {
btrfs_err(fs_info,
"block group %llu len %llu mismatch with chunk %llu len %llu",
found_key.objectid, found_key.offset,
em->start, em->len);
ret = -EUCLEAN;
} else {
ret = 0;
read_extent_buffer(leaf, &bg,
btrfs_item_ptr_offset(leaf, slot),
sizeof(bg));
flags = btrfs_block_group_flags(&bg) &
BTRFS_BLOCK_GROUP_TYPE_MASK;
if (flags != (em->map_lookup->type &
BTRFS_BLOCK_GROUP_TYPE_MASK)) {
btrfs_err(fs_info,
"block group %llu len %llu type flags 0x%llx mismatch with chunk type flags 0x%llx",
found_key.objectid,
found_key.offset, flags,
(BTRFS_BLOCK_GROUP_TYPE_MASK &
em->map_lookup->type));
ret = -EUCLEAN;
} else {
ret = 0;
}
}
free_extent_map(em);
goto out;