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btrfs: tree-checker: Verify block_group_item

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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: Xu Wen <wen.xu@gatech.edu>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Gu Jinxiang <gujx@cn.fujitsu.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Tested-by: Gu Jinxiang <gujx@cn.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Qu Wenruo 2018-07-03 17:10:05 +08:00 committed by David Sterba
parent 6d8ff4e458
commit fce466eab7
3 changed files with 103 additions and 1 deletions
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100
fs/btrfs/tree-checker.c
View File

@ -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;
}

2
fs/btrfs/volumes.c
View File

@ -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) {

2
fs/btrfs/volumes.h
View File

@ -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