diff options
| -rw-r--r-- | fs/ext4/xattr.c | 41 |
1 files changed, 39 insertions, 2 deletions
diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c index 7decaaf27e82..69a1b8c6a2ec 100644 --- a/fs/ext4/xattr.c +++ b/fs/ext4/xattr.c @@ -81,6 +81,8 @@ ext4_xattr_block_cache_find(struct inode *, struct ext4_xattr_header *, struct mb_cache_entry **); static __le32 ext4_xattr_hash_entry(char *name, size_t name_len, __le32 *value, size_t value_count); +static __le32 ext4_xattr_hash_entry_signed(char *name, size_t name_len, __le32 *value, + size_t value_count); static void ext4_xattr_rehash(struct ext4_xattr_header *); static const struct xattr_handler * const ext4_xattr_handler_map[] = { @@ -470,8 +472,21 @@ ext4_xattr_inode_verify_hashes(struct inode *ea_inode, tmp_data = cpu_to_le32(hash); e_hash = ext4_xattr_hash_entry(entry->e_name, entry->e_name_len, &tmp_data, 1); - if (e_hash != entry->e_hash) - return -EFSCORRUPTED; + /* All good? */ + if (e_hash == entry->e_hash) + return 0; + + /* + * Not good. Maybe the entry hash was calculated + * using the buggy signed char version? + */ + e_hash = ext4_xattr_hash_entry_signed(entry->e_name, entry->e_name_len, + &tmp_data, 1); + if (e_hash == entry->e_hash) + return 0; + + /* Still no match - bad */ + return -EFSCORRUPTED; } return 0; } @@ -3091,6 +3106,28 @@ static __le32 ext4_xattr_hash_entry(char *name, size_t name_len, __le32 *value, return cpu_to_le32(hash); } +/* + * ext4_xattr_hash_entry_signed() + * + * Compute the hash of an extended attribute incorrectly. + */ +static __le32 ext4_xattr_hash_entry_signed(char *name, size_t name_len, __le32 *value, size_t value_count) +{ + __u32 hash = 0; + + while (name_len--) { + hash = (hash << NAME_HASH_SHIFT) ^ + (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^ + (signed char)*name++; + } + while (value_count--) { + hash = (hash << VALUE_HASH_SHIFT) ^ + (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^ + le32_to_cpu(*value++); + } + return cpu_to_le32(hash); +} + #undef NAME_HASH_SHIFT #undef VALUE_HASH_SHIFT |