From b9aa52c4cb457e7416cc0c95f475e72ef4a61336 Mon Sep 17 00:00:00 2001 From: Olivier Matz Date: Thu, 6 Jun 2019 09:15:19 +0200 Subject: [PATCH] ipv6: fix EFAULT on sendto with icmpv6 and hdrincl The following code returns EFAULT (Bad address): s = socket(AF_INET6, SOCK_RAW, IPPROTO_ICMPV6); setsockopt(s, SOL_IPV6, IPV6_HDRINCL, 1); sendto(ipv6_icmp6_packet, addr); /* returns -1, errno = EFAULT */ The IPv4 equivalent code works. A workaround is to use IPPROTO_RAW instead of IPPROTO_ICMPV6. The failure happens because 2 bytes are eaten from the msghdr by rawv6_probe_proto_opt() starting from commit 19e3c66b52ca ("ipv6 equivalent of "ipv4: Avoid reading user iov twice after raw_probe_proto_opt""), but at that time it was not a problem because IPV6_HDRINCL was not yet introduced. Only eat these 2 bytes if hdrincl == 0. Fixes: 715f504b1189 ("ipv6: add IPV6_HDRINCL option for raw sockets") Signed-off-by: Olivier Matz Acked-by: Nicolas Dichtel Signed-off-by: David S. Miller --- net/ipv6/raw.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/net/ipv6/raw.c b/net/ipv6/raw.c index af2f9a833c4e..1bb88b4b677b 100644 --- a/net/ipv6/raw.c +++ b/net/ipv6/raw.c @@ -895,11 +895,14 @@ static int rawv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len) opt = ipv6_fixup_options(&opt_space, opt); fl6.flowi6_proto = proto; - rfv.msg = msg; - rfv.hlen = 0; - err = rawv6_probe_proto_opt(&rfv, &fl6); - if (err) - goto out; + + if (!hdrincl) { + rfv.msg = msg; + rfv.hlen = 0; + err = rawv6_probe_proto_opt(&rfv, &fl6); + if (err) + goto out; + } if (!ipv6_addr_any(daddr)) fl6.daddr = *daddr; -- 2.30.2