This is a note to let you know that I've just added the patch titled ipv6: use READ_ONCE() for inet->hdrincl as in ipv4 to the 4.4-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: ipv6-use-read_once-for-inet-hdrincl-as-in-ipv4.patch and it can be found in the queue-4.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 59e3e4b52663a9d97efbce7307f62e4bc5c9ce91 Mon Sep 17 00:00:00 2001 From: Olivier Matz <olivier.matz@xxxxxxxxx> Date: Thu, 6 Jun 2019 09:15:18 +0200 Subject: ipv6: use READ_ONCE() for inet->hdrincl as in ipv4 From: Olivier Matz <olivier.matz@xxxxxxxxx> commit 59e3e4b52663a9d97efbce7307f62e4bc5c9ce91 upstream. As it was done in commit 8f659a03a0ba ("net: ipv4: fix for a race condition in raw_sendmsg") and commit 20b50d79974e ("net: ipv4: emulate READ_ONCE() on ->hdrincl bit-field in raw_sendmsg()") for ipv4, copy the value of inet->hdrincl in a local variable, to avoid introducing a race condition in the next commit. Signed-off-by: Olivier Matz <olivier.matz@xxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/ipv6/raw.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) --- a/net/ipv6/raw.c +++ b/net/ipv6/raw.c @@ -757,6 +757,7 @@ static int rawv6_sendmsg(struct sock *sk int hlimit = -1; int tclass = -1; int dontfrag = -1; + int hdrincl; u16 proto; int err; @@ -770,6 +771,13 @@ static int rawv6_sendmsg(struct sock *sk if (msg->msg_flags & MSG_OOB) return -EOPNOTSUPP; + /* hdrincl should be READ_ONCE(inet->hdrincl) + * but READ_ONCE() doesn't work with bit fields. + * Doing this indirectly yields the same result. + */ + hdrincl = inet->hdrincl; + hdrincl = READ_ONCE(hdrincl); + /* * Get and verify the address. */ @@ -878,7 +886,7 @@ static int rawv6_sendmsg(struct sock *sk fl6.flowi6_oif = np->ucast_oif; security_sk_classify_flow(sk, flowi6_to_flowi(&fl6)); - if (inet->hdrincl) + if (hdrincl) fl6.flowi6_flags |= FLOWI_FLAG_KNOWN_NH; dst = ip6_dst_lookup_flow(sk, &fl6, final_p); @@ -899,7 +907,7 @@ static int rawv6_sendmsg(struct sock *sk goto do_confirm; back_from_confirm: - if (inet->hdrincl) + if (hdrincl) err = rawv6_send_hdrinc(sk, msg, len, &fl6, &dst, msg->msg_flags); else { lock_sock(sk); Patches currently in stable-queue which might be from olivier.matz@xxxxxxxxx are queue-4.4/ipv6-use-read_once-for-inet-hdrincl-as-in-ipv4.patch