isofs: Fix unbounded recursion when processing relocated directories
We did not check relocated directory in any way when processing Rock Ridge 'CL' tag. Thus a corrupted isofs image can possibly have a CL entry pointing to another CL entry leading to possibly unbounded recursion in kernel code and thus stack overflow or deadlocks (if there is a loop created from CL entries). Fix the problem by not allowing CL entry to point to a directory entry with CL entry (such use makes no good sense anyway) and by checking whether CL entry doesn't point to itself. CC: stable@vger.kernel.org Reported-by: Chris Evans <cevans@google.com> Signed-off-by: Jan Kara <jack@suse.cz>
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85cd083b49
commit
410dd3cf4c
3 changed files with 55 additions and 22 deletions
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@ -61,7 +61,7 @@ static void isofs_put_super(struct super_block *sb)
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return;
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}
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static int isofs_read_inode(struct inode *);
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static int isofs_read_inode(struct inode *, int relocated);
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static int isofs_statfs (struct dentry *, struct kstatfs *);
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static struct kmem_cache *isofs_inode_cachep;
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@ -1259,7 +1259,7 @@ static int isofs_read_level3_size(struct inode *inode)
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goto out;
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}
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static int isofs_read_inode(struct inode *inode)
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static int isofs_read_inode(struct inode *inode, int relocated)
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{
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struct super_block *sb = inode->i_sb;
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struct isofs_sb_info *sbi = ISOFS_SB(sb);
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@ -1404,7 +1404,7 @@ static int isofs_read_inode(struct inode *inode)
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*/
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if (!high_sierra) {
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parse_rock_ridge_inode(de, inode);
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parse_rock_ridge_inode(de, inode, relocated);
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/* if we want uid/gid set, override the rock ridge setting */
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if (sbi->s_uid_set)
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inode->i_uid = sbi->s_uid;
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@ -1483,9 +1483,10 @@ static int isofs_iget5_set(struct inode *ino, void *data)
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* offset that point to the underlying meta-data for the inode. The
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* code below is otherwise similar to the iget() code in
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* include/linux/fs.h */
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struct inode *isofs_iget(struct super_block *sb,
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unsigned long block,
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unsigned long offset)
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struct inode *__isofs_iget(struct super_block *sb,
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unsigned long block,
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unsigned long offset,
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int relocated)
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{
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unsigned long hashval;
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struct inode *inode;
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@ -1507,7 +1508,7 @@ struct inode *isofs_iget(struct super_block *sb,
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return ERR_PTR(-ENOMEM);
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if (inode->i_state & I_NEW) {
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ret = isofs_read_inode(inode);
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ret = isofs_read_inode(inode, relocated);
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if (ret < 0) {
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iget_failed(inode);
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inode = ERR_PTR(ret);
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@ -107,7 +107,7 @@ extern int iso_date(char *, int);
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struct inode; /* To make gcc happy */
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extern int parse_rock_ridge_inode(struct iso_directory_record *, struct inode *);
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extern int parse_rock_ridge_inode(struct iso_directory_record *, struct inode *, int relocated);
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extern int get_rock_ridge_filename(struct iso_directory_record *, char *, struct inode *);
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extern int isofs_name_translate(struct iso_directory_record *, char *, struct inode *);
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@ -118,9 +118,24 @@ extern struct dentry *isofs_lookup(struct inode *, struct dentry *, unsigned int
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extern struct buffer_head *isofs_bread(struct inode *, sector_t);
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extern int isofs_get_blocks(struct inode *, sector_t, struct buffer_head **, unsigned long);
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extern struct inode *isofs_iget(struct super_block *sb,
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unsigned long block,
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unsigned long offset);
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struct inode *__isofs_iget(struct super_block *sb,
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unsigned long block,
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unsigned long offset,
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int relocated);
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static inline struct inode *isofs_iget(struct super_block *sb,
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unsigned long block,
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unsigned long offset)
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{
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return __isofs_iget(sb, block, offset, 0);
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}
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static inline struct inode *isofs_iget_reloc(struct super_block *sb,
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unsigned long block,
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unsigned long offset)
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{
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return __isofs_iget(sb, block, offset, 1);
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}
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/* Because the inode number is no longer relevant to finding the
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* underlying meta-data for an inode, we are free to choose a more
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@ -288,12 +288,16 @@ int get_rock_ridge_filename(struct iso_directory_record *de,
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goto out;
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}
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#define RR_REGARD_XA 1
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#define RR_RELOC_DE 2
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static int
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parse_rock_ridge_inode_internal(struct iso_directory_record *de,
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struct inode *inode, int regard_xa)
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struct inode *inode, int flags)
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{
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int symlink_len = 0;
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int cnt, sig;
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unsigned int reloc_block;
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struct inode *reloc;
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struct rock_ridge *rr;
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int rootflag;
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@ -305,7 +309,7 @@ parse_rock_ridge_inode_internal(struct iso_directory_record *de,
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init_rock_state(&rs, inode);
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setup_rock_ridge(de, inode, &rs);
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if (regard_xa) {
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if (flags & RR_REGARD_XA) {
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rs.chr += 14;
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rs.len -= 14;
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if (rs.len < 0)
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@ -485,12 +489,22 @@ parse_rock_ridge_inode_internal(struct iso_directory_record *de,
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"relocated directory\n");
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goto out;
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case SIG('C', 'L'):
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ISOFS_I(inode)->i_first_extent =
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isonum_733(rr->u.CL.location);
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reloc =
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isofs_iget(inode->i_sb,
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ISOFS_I(inode)->i_first_extent,
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0);
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if (flags & RR_RELOC_DE) {
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printk(KERN_ERR
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"ISOFS: Recursive directory relocation "
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"is not supported\n");
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goto eio;
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}
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reloc_block = isonum_733(rr->u.CL.location);
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if (reloc_block == ISOFS_I(inode)->i_iget5_block &&
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ISOFS_I(inode)->i_iget5_offset == 0) {
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printk(KERN_ERR
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"ISOFS: Directory relocation points to "
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"itself\n");
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goto eio;
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}
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ISOFS_I(inode)->i_first_extent = reloc_block;
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reloc = isofs_iget_reloc(inode->i_sb, reloc_block, 0);
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if (IS_ERR(reloc)) {
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ret = PTR_ERR(reloc);
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goto out;
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@ -637,9 +651,11 @@ static char *get_symlink_chunk(char *rpnt, struct rock_ridge *rr, char *plimit)
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return rpnt;
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}
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int parse_rock_ridge_inode(struct iso_directory_record *de, struct inode *inode)
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int parse_rock_ridge_inode(struct iso_directory_record *de, struct inode *inode,
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int relocated)
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{
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int result = parse_rock_ridge_inode_internal(de, inode, 0);
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int flags = relocated ? RR_RELOC_DE : 0;
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int result = parse_rock_ridge_inode_internal(de, inode, flags);
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/*
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* if rockridge flag was reset and we didn't look for attributes
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@ -647,7 +663,8 @@ int parse_rock_ridge_inode(struct iso_directory_record *de, struct inode *inode)
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*/
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if ((ISOFS_SB(inode->i_sb)->s_rock_offset == -1)
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&& (ISOFS_SB(inode->i_sb)->s_rock == 2)) {
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result = parse_rock_ridge_inode_internal(de, inode, 14);
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result = parse_rock_ridge_inode_internal(de, inode,
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flags | RR_REGARD_XA);
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}
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return result;
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}
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