This is a note to let you know that I've just added the patch titled net: ipv4: fix for a race condition in raw_sendmsg to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: net-ipv4-fix-for-a-race-condition-in-raw_sendmsg.patch and it can be found in the queue-4.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From foo@baz Sun Dec 31 11:13:15 CET 2017 From: Mohamed Ghannam <simo.ghannam@xxxxxxxxx> Date: Sun, 10 Dec 2017 03:50:58 +0000 Subject: net: ipv4: fix for a race condition in raw_sendmsg From: Mohamed Ghannam <simo.ghannam@xxxxxxxxx> [ Upstream commit 8f659a03a0ba9289b9aeb9b4470e6fb263d6f483 ] inet->hdrincl is racy, and could lead to uninitialized stack pointer usage, so its value should be read only once. Fixes: c008ba5bdc9f ("ipv4: Avoid reading user iov twice after raw_probe_proto_opt") Signed-off-by: Mohamed Ghannam <simo.ghannam@xxxxxxxxx> Reviewed-by: Eric Dumazet <edumazet@xxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/ipv4/raw.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) --- a/net/ipv4/raw.c +++ b/net/ipv4/raw.c @@ -502,11 +502,16 @@ static int raw_sendmsg(struct sock *sk, int err; struct ip_options_data opt_copy; struct raw_frag_vec rfv; + int hdrincl; err = -EMSGSIZE; if (len > 0xFFFF) goto out; + /* hdrincl should be READ_ONCE(inet->hdrincl) + * but READ_ONCE() doesn't work with bit fields + */ + hdrincl = inet->hdrincl; /* * Check the flags. */ @@ -582,7 +587,7 @@ static int raw_sendmsg(struct sock *sk, /* Linux does not mangle headers on raw sockets, * so that IP options + IP_HDRINCL is non-sense. */ - if (inet->hdrincl) + if (hdrincl) goto done; if (ipc.opt->opt.srr) { if (!daddr) @@ -604,12 +609,12 @@ static int raw_sendmsg(struct sock *sk, flowi4_init_output(&fl4, ipc.oif, sk->sk_mark, tos, RT_SCOPE_UNIVERSE, - inet->hdrincl ? IPPROTO_RAW : sk->sk_protocol, + hdrincl ? IPPROTO_RAW : sk->sk_protocol, inet_sk_flowi_flags(sk) | - (inet->hdrincl ? FLOWI_FLAG_KNOWN_NH : 0), + (hdrincl ? FLOWI_FLAG_KNOWN_NH : 0), daddr, saddr, 0, 0); - if (!inet->hdrincl) { + if (!hdrincl) { rfv.msg = msg; rfv.hlen = 0; @@ -634,7 +639,7 @@ static int raw_sendmsg(struct sock *sk, goto do_confirm; back_from_confirm: - if (inet->hdrincl) + if (hdrincl) err = raw_send_hdrinc(sk, &fl4, msg, len, &rt, msg->msg_flags, &ipc.sockc); Patches currently in stable-queue which might be from simo.ghannam@xxxxxxxxx are queue-4.9/net-ipv4-fix-for-a-race-condition-in-raw_sendmsg.patch