[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>

1 files changed, 8 insertions, 5 deletions

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 8f1f49ceebec..a3a3eecef689 100644
--- 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);