From 51f299dd94bb1e28d03eefbc4fe0b9282f9ee2fa Mon Sep 17 00:00:00 2001 From: Rasmus Villemoes Date: Mon, 13 Nov 2017 00:15:04 +0100 Subject: 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 Signed-off-by: David S. Miller --- net/core/dev.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'net') diff --git a/net/core/dev.c b/net/core/dev.c index 658337bf33e4..1a5d31fdea27 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 -- cgit v1.2.3