Commit d198b277 authored Sep 13, 2021 by Eric Dumazet Committed by David S. Miller Sep 14, 2021

Revert "Revert "ipv4: fix memory leaks in ip_cmsg_send() callers""

This reverts commit d7807a9a.

As mentioned in https://lkml.org/lkml/2021/9/13/1819


5 years old commit 91948309 ("ipv4: fix memory leaks in ip_cmsg_send() callers")
was a correct fix.

  ip_cmsg_send() can loop over multiple cmsghdr()

  If IP_RETOPTS has been successful, but following cmsghdr generates an error,
  we do not free ipc.ok

  If IP_RETOPTS is not successful, we have freed the allocated temporary space,
  not the one currently in ipc.opt.

Sure, code could be refactored, but let's not bring back old bugs.

Fixes: d7807a9a ("Revert "ipv4: fix memory leaks in ip_cmsg_send() callers"")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Yajun Deng <yajun.deng@linux.dev>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 4f884f39

net/ipv4/ip_sockglue.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -279,7 +279,7 @@ int ip_cmsg_send(struct sock sk, struct msghdr msg, struct ipcm_cookie *ipc,
		case IP_RETOPTS:
		err = cmsg->cmsg_len - sizeof(struct cmsghdr);

		/* Our caller is responsible for freeing ipc->opt when err = 0 */
		/* Our caller is responsible for freeing ipc->opt */
		err = ip_options_get(net, &ipc->opt,
		KERNEL_SOCKPTR(CMSG_DATA(cmsg)),
		err < 40 ? err : 40);

net/ipv4/ping.c

+3 −2

Original line number	Diff line number	Diff line
		@@ -727,9 +727,10 @@ static int ping_v4_sendmsg(struct sock sk, struct msghdr msg, size_t len)

		if (msg->msg_controllen) {
		err = ip_cmsg_send(sk, msg, &ipc, false);
		if (unlikely(err))
		if (unlikely(err)) {
		kfree(ipc.opt);
		return err;

		}
		if (ipc.opt)
		free = 1;
		}

net/ipv4/raw.c

+3 −2

Original line number	Diff line number	Diff line
		@@ -562,9 +562,10 @@ static int raw_sendmsg(struct sock sk, struct msghdr msg, size_t len)

		if (msg->msg_controllen) {
		err = ip_cmsg_send(sk, msg, &ipc, false);
		if (unlikely(err))
		if (unlikely(err)) {
		kfree(ipc.opt);
		goto out;

		}
		if (ipc.opt)
		free = 1;
		}

net/ipv4/udp.c

+3 −2

Original line number	Diff line number	Diff line
		@@ -1122,9 +1122,10 @@ int udp_sendmsg(struct sock sk, struct msghdr msg, size_t len)
		if (err > 0)
		err = ip_cmsg_send(sk, msg, &ipc,
		sk->sk_family == AF_INET6);
		if (unlikely(err < 0))
		if (unlikely(err < 0)) {
		kfree(ipc.opt);
		return err;

		}
		if (ipc.opt)
		free = 1;
		connected = 0;