make path_init() unconditionally paired with terminate_walk()
authorAl Viro <viro@zeniv.linux.org.uk>
Mon, 9 Jul 2018 20:27:23 +0000 (16:27 -0400)
committerAl Viro <viro@zeniv.linux.org.uk>
Thu, 12 Jul 2018 14:04:30 +0000 (10:04 -0400)
including the failure exits

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
fs/namei.c

index 8311dce..1b5c58a 100644 (file)
@@ -2125,12 +2125,15 @@ OK:
        }
 }
 
+/* must be paired with terminate_walk() */
 static const char *path_init(struct nameidata *nd, unsigned flags)
 {
        const char *s = nd->name->name;
 
        if (!*s)
                flags &= ~LOOKUP_RCU;
+       if (flags & LOOKUP_RCU)
+               rcu_read_lock();
 
        nd->last_type = LAST_ROOT; /* if there are only slashes... */
        nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT;
@@ -2143,7 +2146,6 @@ static const char *path_init(struct nameidata *nd, unsigned flags)
                nd->path = nd->root;
                nd->inode = inode;
                if (flags & LOOKUP_RCU) {
-                       rcu_read_lock();
                        nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
                        nd->root_seq = nd->seq;
                        nd->m_seq = read_seqbegin(&mount_lock);
@@ -2159,21 +2161,15 @@ static const char *path_init(struct nameidata *nd, unsigned flags)
 
        nd->m_seq = read_seqbegin(&mount_lock);
        if (*s == '/') {
-               if (flags & LOOKUP_RCU)
-                       rcu_read_lock();
                set_root(nd);
                if (likely(!nd_jump_root(nd)))
                        return s;
-               nd->root.mnt = NULL;
-               rcu_read_unlock();
                return ERR_PTR(-ECHILD);
        } else if (nd->dfd == AT_FDCWD) {
                if (flags & LOOKUP_RCU) {
                        struct fs_struct *fs = current->fs;
                        unsigned seq;
 
-                       rcu_read_lock();
-
                        do {
                                seq = read_seqcount_begin(&fs->seq);
                                nd->path = fs->pwd;
@@ -2195,16 +2191,13 @@ static const char *path_init(struct nameidata *nd, unsigned flags)
 
                dentry = f.file->f_path.dentry;
 
-               if (*s) {
-                       if (!d_can_lookup(dentry)) {
-                               fdput(f);
-                               return ERR_PTR(-ENOTDIR);
-                       }
+               if (*s && unlikely(!d_can_lookup(dentry))) {
+                       fdput(f);
+                       return ERR_PTR(-ENOTDIR);
                }
 
                nd->path = f.file->f_path;
                if (flags & LOOKUP_RCU) {
-                       rcu_read_lock();
                        nd->inode = nd->path.dentry->d_inode;
                        nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
                } else {
@@ -2272,8 +2265,10 @@ static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path
        const char *s = path_init(nd, flags);
        int err;
 
-       if (IS_ERR(s))
+       if (IS_ERR(s)) {
+               terminate_walk(nd);
                return PTR_ERR(s);
+       }
 
        if (unlikely(flags & LOOKUP_DOWN)) {
                err = handle_lookup_down(nd);
@@ -2337,8 +2332,10 @@ static int path_parentat(struct nameidata *nd, unsigned flags,
 {
        const char *s = path_init(nd, flags);
        int err;
-       if (IS_ERR(s))
+       if (IS_ERR(s)) {
+               terminate_walk(nd);
                return PTR_ERR(s);
+       }
        err = link_path_walk(s, nd);
        if (!err)
                err = complete_walk(nd);
@@ -2666,8 +2663,10 @@ path_mountpoint(struct nameidata *nd, unsigned flags, struct path *path)
 {
        const char *s = path_init(nd, flags);
        int err;
-       if (IS_ERR(s))
+       if (IS_ERR(s)) {
+               terminate_walk(nd);
                return PTR_ERR(s);
+       }
        while (!(err = link_path_walk(s, nd)) &&
                (err = mountpoint_last(nd)) > 0) {
                s = trailing_symlink(nd);
@@ -3512,6 +3511,7 @@ static struct file *path_openat(struct nameidata *nd,
 
        s = path_init(nd, flags);
        if (IS_ERR(s)) {
+               terminate_walk(nd);
                fput(file);
                return ERR_CAST(s);
        }