[PATCH] cleanup in proc_check_chroot()

proc_check_chroot() does the check in a very unintuitive way (keeping a
copy of the argument, then modifying the argument), and has uncommented
sideeffects.

Signed-off-by: Herbert Poetzl <herbert@13thfloor.at>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 8f1f49c..a3a3eec 100644 (file)
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -534,12 +534,15 @@ static int proc_oom_score(struct task_struct *task, char *buffer)
 
 /* If the process being read is separated by chroot from the reading process,
  * don't let the reader access the threads.
+ *
+ * note: this does dput(root) and mntput(vfsmnt) on exit.
  */
 static int proc_check_chroot(struct dentry *root, struct vfsmount *vfsmnt)
 {
        struct dentry *de, *base;
        struct vfsmount *our_vfsmnt, *mnt;
        int res = 0;
+
        read_lock(&current->fs->lock);
        our_vfsmnt = mntget(current->fs->rootmnt);
        base = dget(current->fs->root);
@@ -549,11 +552,11 @@ static int proc_check_chroot(struct dentry *root, struct vfsmount *vfsmnt)
        de = root;
        mnt = vfsmnt;
 
-       while (vfsmnt != our_vfsmnt) {
-               if (vfsmnt == vfsmnt->mnt_parent)
+       while (mnt != our_vfsmnt) {
+               if (mnt == mnt->mnt_parent)
                        goto out;
-               de = vfsmnt->mnt_mountpoint;
-               vfsmnt = vfsmnt->mnt_parent;
+               de = mnt->mnt_mountpoint;
+               mnt = mnt->mnt_parent;
        }
 
        if (!is_subdir(de, base))
@@ -564,7 +567,7 @@ exit:
        dput(base);
        mntput(our_vfsmnt);
        dput(root);
-       mntput(mnt);
+       mntput(vfsmnt);
        return res;
 out:
        spin_unlock(&vfsmount_lock);