From 51f299dd94bb1e28d03eefbc4fe0b9282f9ee2fa Mon Sep 17 00:00:00 2001
From: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Date: Mon, 13 Nov 2017 00:15:04 +0100
Subject: [PATCH] net: core: improve sanity checking in __dev_alloc_name
__dev_alloc_name is called from the public (and exported)
dev_alloc_name(), so we don't have a guarantee that strlen(name) is at
most IFNAMSIZ. If somebody manages to get __dev_alloc_name called with a
% char beyond the 31st character, we'd be making a snprintf() call that
will very easily crash the kernel (using an appropriate %p extension,
we'll likely dereference some completely bogus pointer).
In the normal case where strlen() is sane, we don't even save anything
by limiting to IFNAMSIZ, so just use strchr().
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
net/core/dev.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/core/dev.c b/net/core/dev.c
index 658337bf33e43..1a5d31fdea273 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1064,7 +1064,7 @@ static int __dev_alloc_name(struct net *net, const char *name, char *buf)
unsigned long *inuse;
struct net_device *d;
- p = strnchr(name, IFNAMSIZ-1, '%');
+ p = strchr(name, '%');
if (p) {
/*
* Verify the string as this thing may have come from
--
2.39.5