diff --git a/fs/ntfs/attrib.c b/fs/ntfs/attrib.c index 5e1ad1cd0118..2d675bf99ca7 100644 --- a/fs/ntfs/attrib.c +++ b/fs/ntfs/attrib.c @@ -921,11 +921,71 @@ char *ntfs_attr_name_get(const struct ntfs_volume *vol, const __le16 *uname, return NULL; } +/* + * ntfs_attr_list_entry_is_valid - sanity check one $ATTRIBUTE_LIST entry + * @ale: the attribute-list entry to check + * @al_end: end of the attribute-list buffer @ale lives in + * + * Verify that @ale is a well-formed attr_list_entry wholly contained in + * [.., @al_end): its fixed header must lie in range before any field is + * dereferenced, its length must be a multiple of 8 that covers the fixed + * header plus the name, the name must lie within the buffer, the entry must + * be in use and carry a live MFT reference. Return true if valid. + */ +bool ntfs_attr_list_entry_is_valid(const struct attr_list_entry *ale, + const u8 *al_end) +{ + const u8 *al = (const u8 *)ale; + u16 ale_len; + + /* The fixed header must be in bounds before it is parsed. */ + if (al + offsetof(struct attr_list_entry, name) > al_end) + return false; + ale_len = le16_to_cpu(ale->length); + /* On-disk entries are 8-byte aligned (see struct attr_list_entry). */ + if (ale_len & 7) + return false; + if (ale->name_offset != sizeof(struct attr_list_entry)) + return false; + if ((u32)ale->name_offset + + (u32)ale->name_length * sizeof(__le16) > ale_len || + al + ale_len > al_end) + return false; + if (ale->type == AT_UNUSED) + return false; + if (MSEQNO_LE(ale->mft_reference) == 0) + return false; + return true; +} + +/* + * ntfs_attr_list_is_valid - sanity check an in-memory $ATTRIBUTE_LIST + * @al_start: start of the attribute list buffer + * @size: length of the attribute list in bytes + * + * Verify that [@al_start, @al_start + @size) is a sequence of valid + * attr_list_entry records (see ntfs_attr_list_entry_is_valid()) that tile the + * buffer exactly. Return true if valid, false otherwise. + */ +bool ntfs_attr_list_is_valid(const u8 *al_start, s64 size) +{ + const u8 *al = al_start; + const u8 *al_end = al_start + size; + + while (al < al_end) { + const struct attr_list_entry *ale = + (const struct attr_list_entry *)al; + + if (!ntfs_attr_list_entry_is_valid(ale, al_end)) + return false; + al += le16_to_cpu(ale->length); + } + return al == al_end; +} + int load_attribute_list(struct ntfs_inode *base_ni, u8 *al_start, const s64 size) { struct inode *attr_vi = NULL; - u8 *al; - struct attr_list_entry *ale; if (!al_start || size <= 0) return -EINVAL; @@ -947,19 +1007,7 @@ int load_attribute_list(struct ntfs_inode *base_ni, u8 *al_start, const s64 size } iput(attr_vi); - for (al = al_start; al < al_start + size; al += le16_to_cpu(ale->length)) { - ale = (struct attr_list_entry *)al; - if (ale->name_offset != sizeof(struct attr_list_entry)) - break; - if (le16_to_cpu(ale->length) <= ale->name_offset + ale->name_length || - al + le16_to_cpu(ale->length) > al_start + size) - break; - if (ale->type == AT_UNUSED) - break; - if (MSEQNO_LE(ale->mft_reference) == 0) - break; - } - if (al != al_start + size) { + if (!ntfs_attr_list_is_valid(al_start, size)) { ntfs_error(base_ni->vol->sb, "Corrupt attribute list, mft = %llu", base_ni->mft_no); return -EIO; diff --git a/fs/ntfs/attrib.h b/fs/ntfs/attrib.h index f7acc7986b09..e2224fbfaabe 100644 --- a/fs/ntfs/attrib.h +++ b/fs/ntfs/attrib.h @@ -71,6 +71,10 @@ int ntfs_attr_lookup(const __le32 type, const __le16 *name, const u32 name_len, const u32 ic, const s64 lowest_vcn, const u8 *val, const u32 val_len, struct ntfs_attr_search_ctx *ctx); +bool ntfs_attr_list_entry_is_valid(const struct attr_list_entry *ale, + const u8 *al_end); +bool ntfs_attr_list_is_valid(const u8 *al_start, s64 size); + int load_attribute_list(struct ntfs_inode *base_ni, u8 *al_start, const s64 size); diff --git a/fs/ntfs/inode.c b/fs/ntfs/inode.c index 9717fb5b4709..8a7798d7f5fc 100644 --- a/fs/ntfs/inode.c +++ b/fs/ntfs/inode.c @@ -848,6 +848,12 @@ static int ntfs_read_locked_inode(struct inode *vi) a->data.resident.value_offset), le32_to_cpu( a->data.resident.value_length)); + /* A resident list is not validated on load; check it now. */ + if (!ntfs_attr_list_is_valid(ni->attr_list, + ni->attr_list_size)) { + ntfs_error(vi->i_sb, "Corrupt attribute list."); + goto unm_err_out; + } } } skip_attr_list_load: