5.4-stable review patch. If anyone has any objections, please let me know.
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From: Marc Dionne marc.dionne@auristor.com
[ Upstream commit 01b2885d9415152bcb12ff1f7788f500a74ea0ed ]
Commit 86a7e0b69bd5 ("net: prevent rewrite of msg_name in sock_sendmsg()") made sock_sendmsg save the incoming msg_name pointer and restore it before returning, to insulate the caller against msg_name being changed by the called code. If the address length was also changed however, we may return with an inconsistent structure where the length doesn't match the address, and attempts to reuse it may lead to lost packets.
For example, a kernel that doesn't have commit 1c5950fc6fe9 ("udp6: fix potential access to stale information") will replace a v4 mapped address with its ipv4 equivalent, and shorten namelen accordingly from 28 to 16. If the caller attempts to reuse the resulting msg structure, it will have the original ipv6 (v4 mapped) address but an incorrect v4 length.
Fixes: 86a7e0b69bd5 ("net: prevent rewrite of msg_name in sock_sendmsg()") Signed-off-by: Marc Dionne marc.dionne@auristor.com Reviewed-by: Willem de Bruijn willemb@google.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- net/socket.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/net/socket.c b/net/socket.c index 38c26e20511d7..e3a50f107d64d 100644 --- a/net/socket.c +++ b/net/socket.c @@ -661,6 +661,7 @@ int sock_sendmsg(struct socket *sock, struct msghdr *msg) { struct sockaddr_storage *save_addr = (struct sockaddr_storage *)msg->msg_name; struct sockaddr_storage address; + int save_len = msg->msg_namelen; int ret;
if (msg->msg_name) { @@ -670,6 +671,7 @@ int sock_sendmsg(struct socket *sock, struct msghdr *msg)
ret = __sock_sendmsg(sock, msg); msg->msg_name = save_addr; + msg->msg_namelen = save_len;
return ret; }