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%3Ba=su...

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@vger.kernel.org know about it.

From foo@baz Sun Dec 31 11:13:15 CET 2017

From: Mohamed Ghannam simo.ghannam@gmail.com 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@gmail.com

[ 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@gmail.com Reviewed-by: Eric Dumazet edumazet@google.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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@gmail.com are

queue-4.9/net-ipv4-fix-for-a-race-condition-in-raw_sendmsg.patch