forked from Minki/linux
btrfs: tree-checker: Check if the file extent end overflows
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>
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@ -132,6 +132,7 @@ static int check_extent_data_item(struct extent_buffer *leaf,
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struct btrfs_file_extent_item *fi;
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u32 sectorsize = fs_info->sectorsize;
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u32 item_size = btrfs_item_size_nr(leaf, slot);
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u64 extent_end;
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if (!IS_ALIGNED(key->offset, sectorsize)) {
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file_extent_err(leaf, slot,
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@ -207,6 +208,16 @@ static int check_extent_data_item(struct extent_buffer *leaf,
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CHECK_FE_ALIGNED(leaf, slot, fi, num_bytes, sectorsize))
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return -EUCLEAN;
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/* Catch extent end overflow */
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if (check_add_overflow(btrfs_file_extent_num_bytes(leaf, fi),
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key->offset, &extent_end)) {
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file_extent_err(leaf, slot,
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"extent end overflow, have file offset %llu extent num bytes %llu",
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key->offset,
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btrfs_file_extent_num_bytes(leaf, fi));
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return -EUCLEAN;
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}
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/*
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* Check that no two consecutive file extent items, in the same leaf,
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* present ranges that overlap each other.
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