From: Qu Wenruo wqu@suse.com
[ Upstream commit 4c094c33c9ed4b8d0d814bd1d7ff78e123d15d00 ]
Under certain conditions, we could have strange file extent item in log tree like:
item 18 key (69599 108 397312) itemoff 15208 itemsize 53 extent data disk bytenr 0 nr 0 extent data offset 0 nr 18446744073709547520 ram 18446744073709547520
The num_bytes + ram_bytes overflow 64 bit type.
For num_bytes part, we can detect such overflow along with file offset (key->offset), as file_offset + num_bytes should never go beyond u64.
For ram_bytes part, it's about the decompressed size of the extent, not directly related to the size. In theory it is OK to have a large value, and put extra limitation on RAM bytes may cause unexpected false alerts.
So in tree-checker, we only check if the file offset and num bytes overflow.
Signed-off-by: Qu Wenruo wqu@suse.com Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/btrfs/tree-checker.c | 11 +++++++++++ 1 file changed, 11 insertions(+)
diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c index 96fce4bef4e7..ccd5706199d7 100644 --- a/fs/btrfs/tree-checker.c +++ b/fs/btrfs/tree-checker.c @@ -132,6 +132,7 @@ static int check_extent_data_item(struct extent_buffer *leaf, struct btrfs_file_extent_item *fi; u32 sectorsize = fs_info->sectorsize; u32 item_size = btrfs_item_size_nr(leaf, slot); + u64 extent_end;
if (!IS_ALIGNED(key->offset, sectorsize)) { file_extent_err(leaf, slot, @@ -207,6 +208,16 @@ static int check_extent_data_item(struct extent_buffer *leaf, CHECK_FE_ALIGNED(leaf, slot, fi, num_bytes, sectorsize)) return -EUCLEAN;
+ /* Catch extent end overflow */ + if (check_add_overflow(btrfs_file_extent_num_bytes(leaf, fi), + key->offset, &extent_end)) { + file_extent_err(leaf, slot, + "extent end overflow, have file offset %llu extent num bytes %llu", + key->offset, + btrfs_file_extent_num_bytes(leaf, fi)); + return -EUCLEAN; + } + /* * Check that no two consecutive file extent items, in the same leaf, * present ranges that overlap each other.