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net: ipv4: fix for a race condition in raw_sendmsg

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inet->hdrincl is racy, and could lead to uninitialized stack pointer
usage, so its value should be read only once.

Fixes: c008ba5bdc ("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>
This commit is contained in:
Mohamed Ghannam 2017-12-10 03:50:58 +00:00 committed by David S. Miller
parent 93c647643b
commit 8f659a03a0
1 changed files with 10 additions and 5 deletions
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15
net/ipv4/raw.c
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@ -513,11 +513,16 @@ static int raw_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
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.
*/
@ -593,7 +598,7 @@ static int raw_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
/* 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)
@ -615,12 +620,12 @@ static int raw_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
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, sk->sk_uid);
if (!inet->hdrincl) {
if (!hdrincl) {
rfv.msg = msg;
rfv.hlen = 0;
@ -645,7 +650,7 @@ static int raw_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
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);