[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <1488289373.9415.251.camel@edumazet-glaptop3.roam.corp.google.com>
Date: Tue, 28 Feb 2017 05:42:53 -0800
From: Eric Dumazet <eric.dumazet@...il.com>
To: Alexander Potapenko <glider@...gle.com>
Cc: dvyukov@...gle.com, kcc@...gle.com, edumazet@...gle.com,
linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH] net: don't call strlen() on the user buffer in
packet_bind_spkt()
On Tue, 2017-02-28 at 05:33 -0800, Eric Dumazet wrote:
> It looks a bug in this implementation of strlcpy() then.
>
Apparently strlcpy(dest, src, size) returns strlen(src), so we can not
use it in this context.
> sizeof(name) is 15.
>
> If you use strncpy(X, uaddr->sa_data, 15) , then you might access
> uaddr->sa_data[14] and this would still be wrong, since sa_data has 14
> bytes only :
>
>
> struct sockaddr {
> sa_family_t sa_family;
> char sa_data[14];
> };
Maybe then :
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 2bd0d1949312c3d71c4b33529316dcfe76fa28f1..d2e7caa79d2604363316c7316864bed1f4971d29 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -3103,7 +3103,7 @@ static int packet_bind_spkt(struct socket *sock, struct sockaddr *uaddr,
int addr_len)
{
struct sock *sk = sock->sk;
- char name[15];
+ char name[sizeof(uaddr->sa_data) + 1];
/*
* Check legality
@@ -3111,7 +3111,8 @@ static int packet_bind_spkt(struct socket *sock, struct sockaddr *uaddr,
if (addr_len != sizeof(struct sockaddr))
return -EINVAL;
- strlcpy(name, uaddr->sa_data, sizeof(name));
+ memcpy(name, uaddr->sa_data, sizeof(uaddr->sa_data));
+ name[sizeof(uaddr->sa_data)] = 0;
return packet_do_bind(sk, name, 0, pkt_sk(sk)->num);
}
Powered by blists - more mailing lists