udp6: fix potential access to stale information
[ Upstream commit 1c5950fc6fe996235f1d18539b9c6b64b597f50f ]
lena wang reported an issue caused by udpv6_sendmsg()
mangling msg->msg_name and msg->msg_namelen, which
are later read from ____sys_sendmsg() :
/*
* If this is sendmmsg() and sending to current destination address was
* successful, remember it.
*/
if (used_address && err >= 0) {
used_address->name_len = msg_sys->msg_namelen;
if (msg_sys->msg_name)
memcpy(&used_address->name, msg_sys->msg_name,
used_address->name_len);
}
udpv6_sendmsg() wants to pretend the remote address family
is AF_INET in order to call udp_sendmsg().
A fix would be to modify the address in-place, instead
of using a local variable, but this could have other side effects.
Instead, restore initial values before we return from udpv6_sendmsg().
Fixes: c71d8ebe7a
("net: Fix security_socket_sendmsg() bypass problem.")
Reported-by: lena wang <lena.wang@mediatek.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Maciej Żenczykowski <maze@google.com>
Link: https://lore.kernel.org/r/20230412130308.1202254-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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@ -1283,9 +1283,11 @@ int udpv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
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msg->msg_name = &sin;
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msg->msg_name = &sin;
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msg->msg_namelen = sizeof(sin);
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msg->msg_namelen = sizeof(sin);
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do_udp_sendmsg:
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do_udp_sendmsg:
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if (__ipv6_only_sock(sk))
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err = __ipv6_only_sock(sk) ?
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return -ENETUNREACH;
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-ENETUNREACH : udp_sendmsg(sk, msg, len);
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return udp_sendmsg(sk, msg, len);
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msg->msg_name = sin6;
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msg->msg_namelen = addr_len;
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return err;
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}
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}
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}
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}
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