From 21d8a15ac333b05f1fecdf9fdc30996be2e11d60 Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Thu, 29 Nov 2012 22:17:21 -0500
Subject: lookup_one_len: don't accept . and ..

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/namei.c b/fs/namei.c
index 937f9d5..5f4cdf3 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2131,6 +2131,11 @@ struct dentry *lookup_one_len(const char *name, struct dentry *base, int len)
 	if (!len)
 		return ERR_PTR(-EACCES);
 
+	if (unlikely(name[0] == '.')) {
+		if (len < 2 || (len == 2 && name[1] == '.'))
+			return ERR_PTR(-EACCES);
+	}
+
 	while (len--) {
 		c = *(const unsigned char *)name++;
 		if (c == '/' || c == '\0')
-- 
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