6.12-stable review patch. If anyone has any objections, please let me know.
------------------
From: Eric Dumazet edumazet@google.com
[ Upstream commit 99a2ace61b211b0be861b07fbaa062fca4b58879 ]
Use RCU to protect accesses to dst->dev from sk_setup_caps() and sk_dst_gso_max_size().
Also use dst_dev_rcu() in ip6_dst_mtu_maybe_forward(), and ip_dst_mtu_maybe_forward().
ip4_dst_hoplimit() can use dst_dev_net_rcu().
Fixes: 4a6ce2b6f2ec ("net: introduce a new function dst_dev_put()") Signed-off-by: Eric Dumazet edumazet@google.com Reviewed-by: David Ahern dsahern@kernel.org Link: https://patch.msgid.link/20250828195823.3958522-6-edumazet@google.com Signed-off-by: Jakub Kicinski kuba@kernel.org [Harshit: Backport to 6.12.y, resolve conflict due to missing commit: 22d6c9eebf2e ("net: Unexport shared functions for DCCP.") in 6.12.y] Signed-off-by: Harshit Mogalapalli harshit.m.mogalapalli@oracle.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- include/net/ip.h | 6 ++++-- include/net/ip6_route.h | 2 +- include/net/route.h | 2 +- net/core/sock.c | 16 ++++++++++------ 4 files changed, 16 insertions(+), 10 deletions(-)
--- a/include/net/ip.h +++ b/include/net/ip.h @@ -470,12 +470,14 @@ static inline unsigned int ip_dst_mtu_ma bool forwarding) { const struct rtable *rt = dst_rtable(dst); + const struct net_device *dev; unsigned int mtu, res; struct net *net;
rcu_read_lock();
- net = dev_net_rcu(dst_dev(dst)); + dev = dst_dev_rcu(dst); + net = dev_net_rcu(dev); if (READ_ONCE(net->ipv4.sysctl_ip_fwd_use_pmtu) || ip_mtu_locked(dst) || !forwarding) { @@ -489,7 +491,7 @@ static inline unsigned int ip_dst_mtu_ma if (mtu) goto out;
- mtu = READ_ONCE(dst_dev(dst)->mtu); + mtu = READ_ONCE(dev->mtu);
if (unlikely(ip_mtu_locked(dst))) { if (rt->rt_uses_gateway && mtu > 576) --- a/include/net/ip6_route.h +++ b/include/net/ip6_route.h @@ -337,7 +337,7 @@ static inline unsigned int ip6_dst_mtu_m
mtu = IPV6_MIN_MTU; rcu_read_lock(); - idev = __in6_dev_get(dst_dev(dst)); + idev = __in6_dev_get(dst_dev_rcu(dst)); if (idev) mtu = READ_ONCE(idev->cnf.mtu6); rcu_read_unlock(); --- a/include/net/route.h +++ b/include/net/route.h @@ -369,7 +369,7 @@ static inline int ip4_dst_hoplimit(const const struct net *net;
rcu_read_lock(); - net = dev_net_rcu(dst_dev(dst)); + net = dst_dev_net_rcu(dst); hoplimit = READ_ONCE(net->ipv4.sysctl_ip_default_ttl); rcu_read_unlock(); } --- a/net/core/sock.c +++ b/net/core/sock.c @@ -2524,7 +2524,7 @@ void sk_free_unlock_clone(struct sock *s } EXPORT_SYMBOL_GPL(sk_free_unlock_clone);
-static u32 sk_dst_gso_max_size(struct sock *sk, struct dst_entry *dst) +static u32 sk_dst_gso_max_size(struct sock *sk, const struct net_device *dev) { bool is_ipv6 = false; u32 max_size; @@ -2534,8 +2534,8 @@ static u32 sk_dst_gso_max_size(struct so !ipv6_addr_v4mapped(&sk->sk_v6_rcv_saddr)); #endif /* pairs with the WRITE_ONCE() in netif_set_gso(_ipv4)_max_size() */ - max_size = is_ipv6 ? READ_ONCE(dst_dev(dst)->gso_max_size) : - READ_ONCE(dst_dev(dst)->gso_ipv4_max_size); + max_size = is_ipv6 ? READ_ONCE(dev->gso_max_size) : + READ_ONCE(dev->gso_ipv4_max_size); if (max_size > GSO_LEGACY_MAX_SIZE && !sk_is_tcp(sk)) max_size = GSO_LEGACY_MAX_SIZE;
@@ -2544,9 +2544,12 @@ static u32 sk_dst_gso_max_size(struct so
void sk_setup_caps(struct sock *sk, struct dst_entry *dst) { + const struct net_device *dev; u32 max_segs = 1;
- sk->sk_route_caps = dst_dev(dst)->features; + rcu_read_lock(); + dev = dst_dev_rcu(dst); + sk->sk_route_caps = dev->features; if (sk_is_tcp(sk)) { struct inet_connection_sock *icsk = inet_csk(sk);
@@ -2562,13 +2565,14 @@ void sk_setup_caps(struct sock *sk, stru sk->sk_route_caps &= ~NETIF_F_GSO_MASK; } else { sk->sk_route_caps |= NETIF_F_SG | NETIF_F_HW_CSUM; - sk->sk_gso_max_size = sk_dst_gso_max_size(sk, dst); + sk->sk_gso_max_size = sk_dst_gso_max_size(sk, dev); /* pairs with the WRITE_ONCE() in netif_set_gso_max_segs() */ - max_segs = max_t(u32, READ_ONCE(dst_dev(dst)->gso_max_segs), 1); + max_segs = max_t(u32, READ_ONCE(dev->gso_max_segs), 1); } } sk->sk_gso_max_segs = max_segs; sk_dst_set(sk, dst); + rcu_read_unlock(); } EXPORT_SYMBOL_GPL(sk_setup_caps);