From 68de007d5ac9df0e3f4f187a179c5c842bb5a2be Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Fri, 12 Jun 2026 05:56:34 +0000 Subject: xfrm: annotate data-races around xfrm_policy_count[] and xfrm_policy_default[] 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 Signed-off-by: Steffen Klassert --- include/net/xfrm.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'include') diff --git a/include/net/xfrm.h b/include/net/xfrm.h index 874409127e29..35a743129329 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) || -- cgit From 40f0b1047918539f0b0f795ac65e35336b4c2c78 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Mon, 15 Jun 2026 09:02:37 +0000 Subject: xfrm: validate selector family and prefixlen during match syzbot reported a shift-out-of-bounds in xfrm_selector_match() due to AF_UNSPEC selector with large prefixlen (e.g. 128) matched against IPv4 flow (when XFRM_STATE_AF_UNSPEC is set). Fix this by: - Rejecting mismatched families in xfrm_selector_match. - Returning false in addr4_match if prefixlen > 32. - Returning false in addr_match if prefixlen > 128 (prevents overflow). Fixes: 3f0ab59e6537 ("xfrm: validate new SA's prefixlen using SA family when sel.family is unset") Reported-by: syzbot+9383b1ff0df4b29ca5e6@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/6a2fbe35.be3f099c.2836ae.0018.GAE@google.com/T/#u Signed-off-by: Eric Dumazet Signed-off-by: Steffen Klassert --- include/net/xfrm.h | 7 +++++++ net/xfrm/xfrm_policy.c | 3 +++ 2 files changed, 10 insertions(+) (limited to 'include') diff --git a/include/net/xfrm.h b/include/net/xfrm.h index 35a743129329..f8c909b0f0c3 100644 --- a/include/net/xfrm.h +++ b/include/net/xfrm.h @@ -943,6 +943,9 @@ static inline bool addr_match(const void *token1, const void *token2, unsigned int pdw; unsigned int pbi; + if (prefixlen > 128) + return false; + pdw = prefixlen >> 5; /* num of whole u32 in prefix */ pbi = prefixlen & 0x1f; /* num of bits in incomplete u32 in prefix */ @@ -967,6 +970,10 @@ static inline bool addr4_match(__be32 a1, __be32 a2, u8 prefixlen) /* C99 6.5.7 (3): u32 << 32 is undefined behaviour */ if (sizeof(long) == 4 && prefixlen == 0) return true; + + if (prefixlen > 32) + return false; + return !((a1 ^ a2) & htonl(~0UL << (32 - prefixlen))); } diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c index 1f4afd580105..639934f30016 100644 --- a/net/xfrm/xfrm_policy.c +++ b/net/xfrm/xfrm_policy.c @@ -242,6 +242,9 @@ __xfrm6_selector_match(const struct xfrm_selector *sel, const struct flowi *fl) bool xfrm_selector_match(const struct xfrm_selector *sel, const struct flowi *fl, unsigned short family) { + if (family != sel->family && sel->family != AF_UNSPEC) + return false; + switch (family) { case AF_INET: return __xfrm4_selector_match(sel, fl); -- cgit