sysctl: fix null checking in bin_dn_node_address()

xiw · torvalds · commit df1778be1a33 · 2013-02-27T19:10:21.000-08:00
The null check of `strchr() + 1' is broken, which is always non-null,
leading to OOB read.  Instead, check the result of strchr().

Signed-off-by: Xi Wang &lt;xi.wang@gmail.com&gt;
Cc: "Eric W. Biederman" &lt;ebiederm@xmission.com&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
diff --git a/kernel/sysctl_binary.c b/kernel/sysctl_binary.c
@@ -1171,9 +1171,10 @@ static ssize_t bin_dn_node_address(struct file *file,
 
 		/* Convert the decnet address to binary */
 		result = -EIO;
-		nodep = strchr(buf, '.') + 1;
+		nodep = strchr(buf, '.');
 		if (!nodep)
 			goto out;
+		++nodep;
 
 		area = simple_strtoul(buf, NULL, 10);
 		node = simple_strtoul(nodep, NULL, 10);
