A crafted image with invalid block group items could make free space cache code to cause panic.
We could early detect such invalid block group item by checking: 1) Item size Fixed value. 2) Block group size (key.offset) We have a up limit on block group item (10G) 3) Chunk objectid Fixed value. 4) Type Only 4 valid type values, DATA, METADATA, SYSTEM and DATA|METADATA. No more than 1 bit set for profile type. 5) Used space No more than block group size. This should allow btrfs to detect and refuse to mount the crafted image. Link: https://bugzilla.kernel.org/show_bug.cgi?id=199849 Reported-by: Xu Wen <wen...@gatech.edu> Signed-off-by: Qu Wenruo <w...@suse.com> --- fs/btrfs/tree-checker.c | 101 ++++++++++++++++++++++++++++++++++++++++ fs/btrfs/volumes.c | 2 +- fs/btrfs/volumes.h | 2 + 3 files changed, 104 insertions(+), 1 deletion(-) diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c index 8d40e7dd8c30..1cd735b099df 100644 --- a/fs/btrfs/tree-checker.c +++ b/fs/btrfs/tree-checker.c @@ -19,6 +19,7 @@ #include "tree-checker.h" #include "disk-io.h" #include "compression.h" +#include "volumes.h" /* * Error message should follow the following format: @@ -353,6 +354,103 @@ static int check_dir_item(struct btrfs_fs_info *fs_info, return 0; } +__printf(4, 5) +__cold +static void block_group_err(const struct btrfs_fs_info *fs_info, + const struct extent_buffer *eb, int slot, + const char *fmt, ...) +{ + struct btrfs_key key; + struct va_format vaf; + va_list args; + + btrfs_item_key_to_cpu(eb, &key, slot); + va_start(args, fmt); + + vaf.fmt = fmt; + vaf.va = &args; + + btrfs_crit(fs_info, + "corrupt %s: root=%llu block=%llu slot=%d bg_start=%llu bg_len=%llu, %pV", + btrfs_header_level(eb) == 0 ? "leaf" : "node", + btrfs_header_owner(eb), btrfs_header_bytenr(eb), slot, + key.objectid, key.offset, &vaf); + va_end(args); +} + +static int check_block_group_item(struct btrfs_fs_info *fs_info, + struct extent_buffer *leaf, + struct btrfs_key *key, int slot) +{ + struct btrfs_block_group_item bgi; + u32 item_size = btrfs_item_size_nr(leaf, slot); + u64 flags; + u64 type_flags; + + /* + * Here we don't really care about unalignment since extent allocator + * can handle it. + * We care more about the size, as if one block group is larger than + * maximum size, it's must be some obvious corruption + */ + if (key->offset > BTRFS_MAX_DATA_CHUNK_SIZE || key->offset == 0) { + block_group_err(fs_info, leaf, slot, + "invalid block group size, have %llu expect (0, %llu]", + key->offset, 10ULL * SZ_1G); + return -EUCLEAN; + } + + if (item_size != sizeof(bgi)) { + block_group_err(fs_info, leaf, slot, + "invalid item size, have %u expect %lu", + item_size, sizeof(bgi)); + return -EUCLEAN; + } + + read_extent_buffer(leaf, &bgi, btrfs_item_ptr_offset(leaf, slot), + sizeof(bgi)); + if (btrfs_block_group_chunk_objectid(&bgi) != + BTRFS_FIRST_CHUNK_TREE_OBJECTID) { + block_group_err(fs_info, leaf, slot, + "invalid block group chunk objectid, have %llu expect %llu", + btrfs_block_group_chunk_objectid(&bgi), + BTRFS_FIRST_CHUNK_TREE_OBJECTID); + return -EUCLEAN; + } + + if (btrfs_block_group_used(&bgi) > key->offset) { + block_group_err(fs_info, leaf, slot, + "invalid block group used, have %llu expect [0, %llu)", + btrfs_block_group_used(&bgi), key->offset); + return -EUCLEAN; + } + + flags = btrfs_block_group_flags(&bgi); + if (hweight64(flags & BTRFS_BLOCK_GROUP_PROFILE_MASK) > 1) { + block_group_err(fs_info, leaf, slot, +"invalid profile flags, have 0x%llx (%lu bits set) expect no more than 1 bit set", + flags & BTRFS_BLOCK_GROUP_PROFILE_MASK, + hweight64(flags & BTRFS_BLOCK_GROUP_PROFILE_MASK)); + return -EUCLEAN; + } + + type_flags = flags & BTRFS_BLOCK_GROUP_TYPE_MASK; + if (type_flags != BTRFS_BLOCK_GROUP_DATA && + type_flags != BTRFS_BLOCK_GROUP_METADATA && + type_flags != BTRFS_BLOCK_GROUP_SYSTEM && + type_flags != (BTRFS_BLOCK_GROUP_METADATA | + BTRFS_BLOCK_GROUP_DATA)) { + block_group_err(fs_info, leaf, slot, +"invalid type flags, have 0x%llx (%lu bits set) expect either 0x%llx, 0x%llx, 0x%llu or 0x%llx", + type_flags, hweight64(type_flags), + BTRFS_BLOCK_GROUP_DATA, BTRFS_BLOCK_GROUP_METADATA, + BTRFS_BLOCK_GROUP_SYSTEM, + BTRFS_BLOCK_GROUP_METADATA | BTRFS_BLOCK_GROUP_DATA); + return -EUCLEAN; + } + return 0; +} + /* * Common point to switch the item-specific validation. */ @@ -374,6 +472,9 @@ static int check_leaf_item(struct btrfs_fs_info *fs_info, case BTRFS_XATTR_ITEM_KEY: ret = check_dir_item(fs_info, leaf, key, slot); break; + case BTRFS_BLOCK_GROUP_ITEM_KEY: + ret = check_block_group_item(fs_info, leaf, key, slot); + break; } return ret; } diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index e034ad9e23b4..b33bf29130b6 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -4690,7 +4690,7 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans, if (type & BTRFS_BLOCK_GROUP_DATA) { max_stripe_size = SZ_1G; - max_chunk_size = 10 * max_stripe_size; + max_chunk_size = BTRFS_MAX_DATA_CHUNK_SIZE; if (!devs_max) devs_max = BTRFS_MAX_DEVS(info); } else if (type & BTRFS_BLOCK_GROUP_METADATA) { diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h index 5139ec8daf4c..77e6004b6cb9 100644 --- a/fs/btrfs/volumes.h +++ b/fs/btrfs/volumes.h @@ -11,6 +11,8 @@ #include <linux/btrfs.h> #include "async-thread.h" +#define BTRFS_MAX_DATA_CHUNK_SIZE (10ULL * SZ_1G) + extern struct mutex uuid_mutex; #define BTRFS_STRIPE_LEN SZ_64K -- 2.18.0 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
