From: Maneesh Soni <maneesh@in.ibm.com>
The patch fixes locking in proc_check_root(). It brings is_subdir() call
under vfsmount_lock. Holding vfsmount_lock will ensure mnt_mountpoint
dentry is intact and the dentry does not go away while it is being checked
in is_subdir().
---
fs/proc/base.c | 7 +++----
1 files changed, 3 insertions(+), 4 deletions(-)
diff -puN fs/proc/base.c~proc_check_root-locking-fix fs/proc/base.c
--- 25/fs/proc/base.c~proc_check_root-locking-fix 2004-01-27 23:50:05.000000000 -0800
+++ 25-akpm/fs/proc/base.c 2004-01-27 23:50:05.000000000 -0800
@@ -425,17 +425,15 @@ static int proc_check_root(struct inode
mnt = vfsmnt;
while (vfsmnt != our_vfsmnt) {
- if (vfsmnt == vfsmnt->mnt_parent) {
- spin_unlock(&vfsmount_lock);
+ if (vfsmnt == vfsmnt->mnt_parent)
goto out;
- }
de = vfsmnt->mnt_mountpoint;
vfsmnt = vfsmnt->mnt_parent;
}
- spin_unlock(&vfsmount_lock);
if (!is_subdir(de, base))
goto out;
+ spin_unlock(&vfsmount_lock);
exit:
dput(base);
@@ -444,6 +442,7 @@ exit:
mntput(mnt);
return res;
out:
+ spin_unlock(&vfsmount_lock);
res = -EACCES;
goto exit;
}
_