From: Eric Dumazet <edumazet@google.com>
To: "David S . Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
Paolo Abeni <pabeni@redhat.com>
Cc: Simon Horman <horms@kernel.org>,
netdev@vger.kernel.org, eric.dumazet@gmail.com,
Eric Dumazet <edumazet@google.com>,
syzbot+d85ba1c732720b9a4097@syzkaller.appspotmail.com,
Steffen Klassert <steffen.klassert@secunet.com>,
Herbert Xu <herbert@gondor.apana.org.au>
Subject: [PATCH net] xfrm: annotate data-races around xfrm_policy_count[] and xfrm_policy_default[]
Date: Fri, 12 Jun 2026 05:56:34 +0000 [thread overview]
Message-ID: <20260612055634.3560352-1-edumazet@google.com> (raw)
KCSAN reported a data race involving net->xfrm.policy_count access.
Add missing READ_ONCE()/WRITE_ONCE() annotations on
xfrm_policy_count and xfrm_policy_default.
Fixes: 2518c7c2b3d7 ("[XFRM]: Hash policies when non-prefixed.")
Reported-by: syzbot+d85ba1c732720b9a4097@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/6a2b9e96.99669fcc.12a77b.0006.GAE@google.com/T/#u
Signed-off-by: Eric Dumazet <edumazet@google.com>
---
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
---
include/net/xfrm.h | 8 ++++----
net/xfrm/xfrm_policy.c | 24 ++++++++++++------------
net/xfrm/xfrm_user.c | 18 +++++++++---------
3 files changed, 25 insertions(+), 25 deletions(-)
diff --git a/include/net/xfrm.h b/include/net/xfrm.h
index 874409127e292197c17dbac4686efdd5ff56c185..35a7431293298a9eb7f82c8a865ca45e227e81e1 100644
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -1250,8 +1250,8 @@ int __xfrm_policy_check(struct sock *, int dir, struct sk_buff *skb,
static inline bool __xfrm_check_nopolicy(struct net *net, struct sk_buff *skb,
int dir)
{
- if (!net->xfrm.policy_count[dir] && !secpath_exists(skb))
- return net->xfrm.policy_default[dir] == XFRM_USERPOLICY_ACCEPT;
+ if (!READ_ONCE(net->xfrm.policy_count[dir]) && !secpath_exists(skb))
+ return READ_ONCE(net->xfrm.policy_default[dir]) == XFRM_USERPOLICY_ACCEPT;
return false;
}
@@ -1351,8 +1351,8 @@ static inline int xfrm_route_forward(struct sk_buff *skb, unsigned short family)
{
struct net *net = dev_net(skb->dev);
- if (!net->xfrm.policy_count[XFRM_POLICY_OUT] &&
- net->xfrm.policy_default[XFRM_POLICY_OUT] == XFRM_USERPOLICY_ACCEPT)
+ if (!READ_ONCE(net->xfrm.policy_count[XFRM_POLICY_OUT]) &&
+ READ_ONCE(net->xfrm.policy_default[XFRM_POLICY_OUT]) == XFRM_USERPOLICY_ACCEPT)
return true;
return (skb_dst(skb)->flags & DST_NOXFRM) ||
diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 95954442569290719b9fdb7b0f9462d70b5d755e..1f4afd580105f97094c6ad8d10001912f67cc731 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -685,7 +685,7 @@ static void xfrm_byidx_resize(struct net *net)
static inline int xfrm_bydst_should_resize(struct net *net, int dir, int *total)
{
- unsigned int cnt = net->xfrm.policy_count[dir];
+ unsigned int cnt = READ_ONCE(net->xfrm.policy_count[dir]);
unsigned int hmask = net->xfrm.policy_bydst[dir].hmask;
if (total)
@@ -711,12 +711,12 @@ static inline int xfrm_byidx_should_resize(struct net *net, int total)
void xfrm_spd_getinfo(struct net *net, struct xfrmk_spdinfo *si)
{
- si->incnt = net->xfrm.policy_count[XFRM_POLICY_IN];
- si->outcnt = net->xfrm.policy_count[XFRM_POLICY_OUT];
- si->fwdcnt = net->xfrm.policy_count[XFRM_POLICY_FWD];
- si->inscnt = net->xfrm.policy_count[XFRM_POLICY_IN+XFRM_POLICY_MAX];
- si->outscnt = net->xfrm.policy_count[XFRM_POLICY_OUT+XFRM_POLICY_MAX];
- si->fwdscnt = net->xfrm.policy_count[XFRM_POLICY_FWD+XFRM_POLICY_MAX];
+ si->incnt = READ_ONCE(net->xfrm.policy_count[XFRM_POLICY_IN]);
+ si->outcnt = READ_ONCE(net->xfrm.policy_count[XFRM_POLICY_OUT]);
+ si->fwdcnt = READ_ONCE(net->xfrm.policy_count[XFRM_POLICY_FWD]);
+ si->inscnt = READ_ONCE(net->xfrm.policy_count[XFRM_POLICY_IN+XFRM_POLICY_MAX]);
+ si->outscnt = READ_ONCE(net->xfrm.policy_count[XFRM_POLICY_OUT+XFRM_POLICY_MAX]);
+ si->fwdscnt = READ_ONCE(net->xfrm.policy_count[XFRM_POLICY_FWD+XFRM_POLICY_MAX]);
si->spdhcnt = net->xfrm.policy_idx_hmask;
si->spdhmcnt = xfrm_policy_hashmax;
}
@@ -2318,7 +2318,7 @@ static void __xfrm_policy_link(struct xfrm_policy *pol, int dir)
}
list_add(&pol->walk.all, &net->xfrm.policy_all);
- net->xfrm.policy_count[dir]++;
+ WRITE_ONCE(net->xfrm.policy_count[dir], net->xfrm.policy_count[dir] + 1);
xfrm_pol_hold(pol);
}
@@ -2337,7 +2337,7 @@ static struct xfrm_policy *__xfrm_policy_unlink(struct xfrm_policy *pol,
}
list_del_init(&pol->walk.all);
- net->xfrm.policy_count[dir]--;
+ WRITE_ONCE(net->xfrm.policy_count[dir], net->xfrm.policy_count[dir] - 1);
return pol;
}
@@ -3222,7 +3222,7 @@ struct dst_entry *xfrm_lookup_with_ifid(struct net *net,
/* To accelerate a bit... */
if (!if_id && ((dst_orig->flags & DST_NOXFRM) ||
- !net->xfrm.policy_count[XFRM_POLICY_OUT]))
+ !READ_ONCE(net->xfrm.policy_count[XFRM_POLICY_OUT])))
goto nopol;
xdst = xfrm_bundle_lookup(net, fl, family, dir, &xflo, if_id);
@@ -3296,7 +3296,7 @@ struct dst_entry *xfrm_lookup_with_ifid(struct net *net,
nopol:
if ((!dst_orig->dev || !(dst_orig->dev->flags & IFF_LOOPBACK)) &&
- net->xfrm.policy_default[dir] == XFRM_USERPOLICY_BLOCK) {
+ READ_ONCE(net->xfrm.policy_default[dir]) == XFRM_USERPOLICY_BLOCK) {
err = -EPERM;
goto error;
}
@@ -3750,7 +3750,7 @@ int __xfrm_policy_check(struct sock *sk, int dir, struct sk_buff *skb,
const bool is_crypto_offload = sp &&
(xfrm_input_state(skb)->xso.type == XFRM_DEV_OFFLOAD_CRYPTO);
- if (net->xfrm.policy_default[dir] == XFRM_USERPOLICY_BLOCK) {
+ if (READ_ONCE(net->xfrm.policy_default[dir]) == XFRM_USERPOLICY_BLOCK) {
XFRM_INC_STATS(net, LINUX_MIB_XFRMINNOPOLS);
return 0;
}
diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index 71a4b7278eba92a7014f877428a587587d0fd476..8de2ebb0f9d7940b28802fc1421f21312df698fe 100644
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -2485,9 +2485,9 @@ static int xfrm_notify_userpolicy(struct net *net)
}
up = nlmsg_data(nlh);
- up->in = net->xfrm.policy_default[XFRM_POLICY_IN];
- up->fwd = net->xfrm.policy_default[XFRM_POLICY_FWD];
- up->out = net->xfrm.policy_default[XFRM_POLICY_OUT];
+ up->in = READ_ONCE(net->xfrm.policy_default[XFRM_POLICY_IN]);
+ up->fwd = READ_ONCE(net->xfrm.policy_default[XFRM_POLICY_FWD]);
+ up->out = READ_ONCE(net->xfrm.policy_default[XFRM_POLICY_OUT]);
nlmsg_end(skb, nlh);
@@ -2511,13 +2511,13 @@ static int xfrm_set_default(struct sk_buff *skb, struct nlmsghdr *nlh,
struct xfrm_userpolicy_default *up = nlmsg_data(nlh);
if (xfrm_userpolicy_is_valid(up->in))
- net->xfrm.policy_default[XFRM_POLICY_IN] = up->in;
+ WRITE_ONCE(net->xfrm.policy_default[XFRM_POLICY_IN], up->in);
if (xfrm_userpolicy_is_valid(up->fwd))
- net->xfrm.policy_default[XFRM_POLICY_FWD] = up->fwd;
+ WRITE_ONCE(net->xfrm.policy_default[XFRM_POLICY_FWD], up->fwd);
if (xfrm_userpolicy_is_valid(up->out))
- net->xfrm.policy_default[XFRM_POLICY_OUT] = up->out;
+ WRITE_ONCE(net->xfrm.policy_default[XFRM_POLICY_OUT], up->out);
rt_genid_bump_all(net);
@@ -2547,9 +2547,9 @@ static int xfrm_get_default(struct sk_buff *skb, struct nlmsghdr *nlh,
}
r_up = nlmsg_data(r_nlh);
- r_up->in = net->xfrm.policy_default[XFRM_POLICY_IN];
- r_up->fwd = net->xfrm.policy_default[XFRM_POLICY_FWD];
- r_up->out = net->xfrm.policy_default[XFRM_POLICY_OUT];
+ r_up->in = READ_ONCE(net->xfrm.policy_default[XFRM_POLICY_IN]);
+ r_up->fwd = READ_ONCE(net->xfrm.policy_default[XFRM_POLICY_FWD]);
+ r_up->out = READ_ONCE(net->xfrm.policy_default[XFRM_POLICY_OUT]);
nlmsg_end(r_skb, r_nlh);
return nlmsg_unicast(xfrm_net_nlsk(net, skb), r_skb, portid);
--
2.54.0.1136.gdb2ca164c4-goog
next reply other threads:[~2026-06-12 5:56 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-12 5:56 Eric Dumazet [this message]
2026-06-12 12:27 ` [PATCH net] xfrm: annotate data-races around xfrm_policy_count[] and xfrm_policy_default[] Herbert Xu
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20260612055634.3560352-1-edumazet@google.com \
--to=edumazet@google.com \
--cc=davem@davemloft.net \
--cc=eric.dumazet@gmail.com \
--cc=herbert@gondor.apana.org.au \
--cc=horms@kernel.org \
--cc=kuba@kernel.org \
--cc=netdev@vger.kernel.org \
--cc=pabeni@redhat.com \
--cc=steffen.klassert@secunet.com \
--cc=syzbot+d85ba1c732720b9a4097@syzkaller.appspotmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox