From c926093ec516f5d316ecdf8c1be11f577ac71b85 Mon Sep 17 00:00:00 2001 From: David Sterba Date: Tue, 30 Sep 2014 19:16:47 +0200 Subject: [PATCH] btrfs: add more superblock checks Populate btrfs_check_super_valid() with checks that try to verify consistency of superblock by additional conditions that may arise from corrupted devices or bitflips. Some of tests are only hints and issue warnings instead of failing the mount, basically when the checks are derived from the data found in the superblock. Tested on a broken image provided by Qu. Reported-by: Qu Wenruo Signed-off-by: David Sterba Signed-off-by: Chris Mason --- fs/btrfs/disk-io.c | 67 ++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 65 insertions(+), 2 deletions(-) diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 09b3c8a0c790..fc8dfaa27967 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -3817,10 +3817,73 @@ int btrfs_read_buffer(struct extent_buffer *buf, u64 parent_transid) static int btrfs_check_super_valid(struct btrfs_fs_info *fs_info, int read_only) { + struct btrfs_super_block *sb = fs_info->super_copy; + int ret = 0; + + if (sb->root_level > BTRFS_MAX_LEVEL) { + printk(KERN_ERR "BTRFS: tree_root level too big: %d > %d\n", + sb->root_level, BTRFS_MAX_LEVEL); + ret = -EINVAL; + } + if (sb->chunk_root_level > BTRFS_MAX_LEVEL) { + printk(KERN_ERR "BTRFS: chunk_root level too big: %d > %d\n", + sb->chunk_root_level, BTRFS_MAX_LEVEL); + ret = -EINVAL; + } + if (sb->log_root_level > BTRFS_MAX_LEVEL) { + printk(KERN_ERR "BTRFS: log_root level too big: %d > %d\n", + sb->log_root_level, BTRFS_MAX_LEVEL); + ret = -EINVAL; + } + /* - * Placeholder for checks + * The common minimum, we don't know if we can trust the nodesize/sectorsize + * items yet, they'll be verified later. Issue just a warning. */ - return 0; + if (!IS_ALIGNED(sb->root, 4096)) + printk(KERN_WARNING "BTRFS: tree_root block unaligned: %llu\n", + sb->root); + if (!IS_ALIGNED(sb->chunk_root, 4096)) + printk(KERN_WARNING "BTRFS: tree_root block unaligned: %llu\n", + sb->chunk_root); + if (!IS_ALIGNED(sb->log_root, 4096)) + printk(KERN_WARNING "BTRFS: tree_root block unaligned: %llu\n", + sb->log_root); + + if (memcmp(fs_info->fsid, sb->dev_item.fsid, BTRFS_UUID_SIZE) != 0) { + printk(KERN_ERR "BTRFS: dev_item UUID does not match fsid: %pU != %pU\n", + fs_info->fsid, sb->dev_item.fsid); + ret = -EINVAL; + } + + /* + * Hint to catch really bogus numbers, bitflips or so, more exact checks are + * done later + */ + if (sb->num_devices > (1UL << 31)) + printk(KERN_WARNING "BTRFS: suspicious number of devices: %llu\n", + sb->num_devices); + + if (sb->bytenr != BTRFS_SUPER_INFO_OFFSET) { + printk(KERN_ERR "BTRFS: super offset mismatch %llu != %u\n", + sb->bytenr, BTRFS_SUPER_INFO_OFFSET); + ret = -EINVAL; + } + + /* + * The generation is a global counter, we'll trust it more than the others + * but it's still possible that it's the one that's wrong. + */ + if (sb->generation < sb->chunk_root_generation) + printk(KERN_WARNING + "BTRFS: suspicious: generation < chunk_root_generation: %llu < %llu\n", + sb->generation, sb->chunk_root_generation); + if (sb->generation < sb->cache_generation && sb->cache_generation != (u64)-1) + printk(KERN_WARNING + "BTRFS: suspicious: generation < cache_generation: %llu < %llu\n", + sb->generation, sb->cache_generation); + + return ret; } static void btrfs_error_commit_super(struct btrfs_root *root)