> -----Original Message----- > From: linux-btrfs-ow...@vger.kernel.org > [mailto:linux-btrfs-ow...@vger.kernel.org] On Behalf Of Qu Wenruo > Sent: Tuesday, July 03, 2018 5:10 PM > To: linux-btrfs@vger.kernel.org > Subject: [PATCH 1/5] btrfs: tree-checker: Verify block_group_item > > 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 > --
Tested-by: Gu Jinxiang <g...@cn.fujitsu.com> > 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 >
