udp: must lock the socket in udp_disconnect()
Baozeng Ding reported KASAN traces showing uses after free in
udp_lib_get_port() and other related UDP functions.
A CONFIG_DEBUG_PAGEALLOC=y kernel would eventually crash.
I could write a reproducer with two threads doing :
static int sock_fd;
static void *thr1(void *arg)
{
for (;;) {
connect(sock_fd, (const struct sockaddr *)arg,
sizeof(struct sockaddr_in));
}
}
static void *thr2(void *arg)
{
struct sockaddr_in unspec;
for (;;) {
memset(&unspec, 0, sizeof(unspec));
connect(sock_fd, (const struct sockaddr *)&unspec,
sizeof(unspec));
}
}
Problem is that udp_disconnect() could run without holding socket lock,
and this was causing list corruptions.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Baozeng Ding <sploving1@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c
index 7cf7d6e..205e200 100644
--- a/net/ipv4/ping.c
+++ b/net/ipv4/ping.c
@@ -994,7 +994,7 @@ struct proto ping_prot = {
.init = ping_init_sock,
.close = ping_close,
.connect = ip4_datagram_connect,
- .disconnect = udp_disconnect,
+ .disconnect = __udp_disconnect,
.setsockopt = ip_setsockopt,
.getsockopt = ip_getsockopt,
.sendmsg = ping_v4_sendmsg,