Commit fce466ea authored by Qu Wenruo's avatar Qu Wenruo Committed by David Sterba
Browse files

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 detect such invalid block group item by checking:
1) Item size
   Known fixed value.
2) Block group size (key.offset)
   We have an upper limit on block group item (10G)
3) Chunk objectid
   Known 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 the 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: default avatarXu Wen <wen.xu@gatech.edu>
Signed-off-by: default avatarQu Wenruo <wqu@suse.com>
Reviewed-by: default avatarGu Jinxiang <gujx@cn.fujitsu.com>
Reviewed-by: default avatarNikolay Borisov <nborisov@suse.com>
Tested-by: default avatarGu Jinxiang <gujx@cn.fujitsu.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 6d8ff4e4

fs/btrfs/tree-checker.c

+100 −0
Original line number Diff line number Diff line
@@ -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 +354,102 @@ 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;



	/*

	 * Here we don't really care about alignment 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, BTRFS_MAX_DATA_CHUNK_SIZE);

		return -EUCLEAN;

	}



	if (item_size != sizeof(bgi)) {

		block_group_err(fs_info, leaf, slot,

			"invalid item size, have %u expect %zu",

				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 & BTRFS_BLOCK_GROUP_TYPE_MASK;

	if (type != BTRFS_BLOCK_GROUP_DATA &&

	    type != BTRFS_BLOCK_GROUP_METADATA &&

	    type != BTRFS_BLOCK_GROUP_SYSTEM &&

	    type != (BTRFS_BLOCK_GROUP_METADATA |

			   BTRFS_BLOCK_GROUP_DATA)) {

		block_group_err(fs_info, leaf, slot,

"invalid type, have 0x%llx (%lu bits set) expect either 0x%llx, 0x%llx, 0x%llu or 0x%llx",

			type, hweight64(type),

			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 +471,9 @@ 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;

}

fs/btrfs/volumes.c

+1 −1
Original line number Diff line number Diff line
@@ -4692,7 +4692,7 @@ 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) {

fs/btrfs/volumes.h

+2 −0
Original line number Diff line number Diff line
@@ -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

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