From: R. Parameswaran Date: Thu, 13 Apr 2017 01:31:04 +0000 (-0700) Subject: l2tp: device MTU setup, tunnel socket needs a lock X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=57240d007816486131bee88cd474c2a71f0fe224;p=openwrt%2Fstaging%2Fblogic.git l2tp: device MTU setup, tunnel socket needs a lock The MTU overhead calculation in L2TP device set-up merged via commit b784e7ebfce8cfb16c6f95e14e8532d0768ab7ff needs to be adjusted to lock the tunnel socket while referencing the sub-data structures to derive the socket's IP overhead. Reported-by: Guillaume Nault Tested-by: Guillaume Nault Signed-off-by: R. Parameswaran Signed-off-by: David S. Miller --- diff --git a/include/linux/net.h b/include/linux/net.h index a42fab24c8af..abcfa46a2bd9 100644 --- a/include/linux/net.h +++ b/include/linux/net.h @@ -298,7 +298,7 @@ int kernel_sendpage(struct socket *sock, struct page *page, int offset, int kernel_sock_ioctl(struct socket *sock, int cmd, unsigned long arg); int kernel_sock_shutdown(struct socket *sock, enum sock_shutdown_cmd how); -/* Following routine returns the IP overhead imposed by a socket. */ +/* Routine returns the IP overhead imposed by a (caller-protected) socket. */ u32 kernel_sock_ip_overhead(struct sock *sk); #define MODULE_ALIAS_NETPROTO(proto) \ diff --git a/net/l2tp/l2tp_eth.c b/net/l2tp/l2tp_eth.c index 138566a63123..b722d559c544 100644 --- a/net/l2tp/l2tp_eth.c +++ b/net/l2tp/l2tp_eth.c @@ -225,7 +225,9 @@ static void l2tp_eth_adjust_mtu(struct l2tp_tunnel *tunnel, dev->needed_headroom += session->hdr_len; return; } + lock_sock(tunnel->sock); l3_overhead = kernel_sock_ip_overhead(tunnel->sock); + release_sock(tunnel->sock); if (l3_overhead == 0) { /* L3 Overhead couldn't be identified, this could be * because tunnel->sock was NULL or the socket's diff --git a/net/socket.c b/net/socket.c index eea997036ada..c2564eb25c6b 100644 --- a/net/socket.c +++ b/net/socket.c @@ -3360,7 +3360,7 @@ EXPORT_SYMBOL(kernel_sock_shutdown); /* This routine returns the IP overhead imposed by a socket i.e. * the length of the underlying IP header, depending on whether * this is an IPv4 or IPv6 socket and the length from IP options turned - * on at the socket. + * on at the socket. Assumes that the caller has a lock on the socket. */ u32 kernel_sock_ip_overhead(struct sock *sk) {