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author | Qu Wenruo <wqu@suse.com> | 2019-03-08 14:20:03 +0800 |
---|---|---|
committer | David Sterba <dsterba@suse.com> | 2019-04-29 19:02:32 +0200 |
commit | ab4ba2e133463c702b37242560d7fabedd2dc750 (patch) | |
tree | c4308266c635ddecb044ee96ccd7ca7bb453e001 /fs/btrfs/tree-checker.c | |
parent | 075cb3c78fe7976c9f29ca1fa23f9728634ecefc (diff) | |
download | linux-ab4ba2e133463c702b37242560d7fabedd2dc750.tar.gz linux-ab4ba2e133463c702b37242560d7fabedd2dc750.tar.bz2 linux-ab4ba2e133463c702b37242560d7fabedd2dc750.zip |
btrfs: tree-checker: Verify dev item
[BUG]
For fuzzed image whose DEV_ITEM has invalid total_bytes as 0, then
kernel will just panic:
BUG: unable to handle kernel NULL pointer dereference at 0000000000000098
#PF error: [normal kernel read fault]
PGD 800000022b2bd067 P4D 800000022b2bd067 PUD 22b2bc067 PMD 0
Oops: 0000 [#1] SMP PTI
CPU: 0 PID: 1106 Comm: mount Not tainted 5.0.0-rc8+ #9
RIP: 0010:btrfs_verify_dev_extents+0x2a5/0x5a0
Call Trace:
open_ctree+0x160d/0x2149
btrfs_mount_root+0x5b2/0x680
[CAUSE]
If device extent verification finds a deivce with 0 total_bytes, then it
assumes it's a seed dummy, then search for seed devices.
But in this case, there is no seed device at all, causing NULL pointer.
[FIX]
Since this is caused by fuzzed image, let's go the tree-check way, just
add a new verification for device item.
Reported-by: Yoon Jungyeon <jungyeon@gatech.edu>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=202691
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs/tree-checker.c')
-rw-r--r-- | fs/btrfs/tree-checker.c | 74 |
1 files changed, 74 insertions, 0 deletions
diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c index 33d04fc4d280..00ab4e783b9f 100644 --- a/fs/btrfs/tree-checker.c +++ b/fs/btrfs/tree-checker.c @@ -600,6 +600,77 @@ int btrfs_check_chunk_valid(struct btrfs_fs_info *fs_info, return 0; } +__printf(4, 5) +__cold +static void dev_item_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 devid=%llu %pV", + btrfs_header_level(eb) == 0 ? "leaf" : "node", + btrfs_header_owner(eb), btrfs_header_bytenr(eb), slot, + key.objectid, &vaf); + va_end(args); +} + +static int check_dev_item(struct btrfs_fs_info *fs_info, + struct extent_buffer *leaf, + struct btrfs_key *key, int slot) +{ + struct btrfs_dev_item *ditem; + u64 max_devid = max(BTRFS_MAX_DEVS(fs_info), BTRFS_MAX_DEVS_SYS_CHUNK); + + if (key->objectid != BTRFS_DEV_ITEMS_OBJECTID) { + dev_item_err(fs_info, leaf, slot, + "invalid objectid: has=%llu expect=%llu", + key->objectid, BTRFS_DEV_ITEMS_OBJECTID); + return -EUCLEAN; + } + if (key->offset > max_devid) { + dev_item_err(fs_info, leaf, slot, + "invalid devid: has=%llu expect=[0, %llu]", + key->offset, max_devid); + return -EUCLEAN; + } + ditem = btrfs_item_ptr(leaf, slot, struct btrfs_dev_item); + if (btrfs_device_id(leaf, ditem) != key->offset) { + dev_item_err(fs_info, leaf, slot, + "devid mismatch: key has=%llu item has=%llu", + key->offset, btrfs_device_id(leaf, ditem)); + return -EUCLEAN; + } + + /* + * For device total_bytes, we don't have reliable way to check it, as + * it can be 0 for device removal. Device size check can only be done + * by dev extents check. + */ + if (btrfs_device_bytes_used(leaf, ditem) > + btrfs_device_total_bytes(leaf, ditem)) { + dev_item_err(fs_info, leaf, slot, + "invalid bytes used: have %llu expect [0, %llu]", + btrfs_device_bytes_used(leaf, ditem), + btrfs_device_total_bytes(leaf, ditem)); + return -EUCLEAN; + } + /* + * Remaining members like io_align/type/gen/dev_group aren't really + * utilized. Skip them to make later usage of them easier. + */ + return 0; +} + /* * Common point to switch the item-specific validation. */ @@ -630,6 +701,9 @@ static int check_leaf_item(struct btrfs_fs_info *fs_info, ret = btrfs_check_chunk_valid(fs_info, leaf, chunk, key->offset); break; + case BTRFS_DEV_ITEM_KEY: + ret = check_dev_item(fs_info, leaf, key, slot); + break; } return ret; } |