[PATCH] missing check in do_add_mount()

Make sure that we don't end up with symlink mounted over something (mount --bind is safe since we use LOOKUP_FOLLOW in pathname resolution there).

[PATCH] missing check in do_add_mount()
Make sure that we don't end up with symlink mounted over something (mount --bind is safe since we use LOOKUP_FOLLOW in pathname resolution there).
d2a4a177 · Alexander Viro · David S. Miller · 4143a413 · d2a4a177
Commit d2a4a177 authored Mar 18, 2004 by Alexander Viro Committed by David S. Miller Mar 18, 2004
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fs/namespace.c fs/namespace.c +4 -0

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--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -681,6 +681,10 @@ static int do_add_mount(struct nameidata *nd, char *type, int flags,
 	if (nd->mnt->mnt_sb == mnt->mnt_sb && nd->mnt->mnt_root == nd->dentry)
 		goto unlock;

+	err = -EINVAL;
+	if (S_ISLNK(mnt->mnt_root->d_inode->i_mode))
+		goto unlock;
+
 	mnt->mnt_flags = mnt_flags;
 	err = graft_tree(mnt, nd);
 unlock: