3.16.55-rc1 review patch. If anyone has any objections, please let me know.
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From: Mohamed Ghannam simo.ghannam@gmail.com
commit 8f659a03a0ba9289b9aeb9b4470e6fb263d6f483 upstream.
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 [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- net/ipv4/raw.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-)
--- a/net/ipv4/raw.c +++ b/net/ipv4/raw.c @@ -490,11 +490,16 @@ static int raw_sendmsg(struct kiocb *ioc 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. */ @@ -569,7 +574,7 @@ static int raw_sendmsg(struct kiocb *ioc /* 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) @@ -591,12 +596,12 @@ static int raw_sendmsg(struct kiocb *ioc
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.iov = msg->msg_iov; rfv.hlen = 0;
@@ -621,7 +626,7 @@ static int raw_sendmsg(struct kiocb *ioc goto do_confirm; back_from_confirm:
- if (inet->hdrincl) + if (hdrincl) err = raw_send_hdrinc(sk, &fl4, msg->msg_iov, len, &rt, msg->msg_flags);