@@ -67,6 +67,7 @@ void dst_init(struct dst_entry *dst, struct dst_ops *ops,
#endif
dst->lwtstate = NULL;
rcuref_init(&dst->__rcuref, initial_ref);
+ INIT_LIST_HEAD(&dst->rt_uncached);
dst->__use = 0;
dst->lastuse = jiffies;
dst->flags = flags;
@@ -1644,7 +1644,6 @@ struct rtable *rt_dst_alloc(struct net_device *dev,
rt->rt_uses_gateway = 0;
rt->rt_gw_family = 0;
rt->rt_gw4 = 0;
- INIT_LIST_HEAD(&rt->dst.rt_uncached);
rt->dst.output = ip_output;
if (flags & RTCF_LOCAL)
@@ -1675,7 +1674,6 @@ struct rtable *rt_dst_clone(struct net_device *dev, struct rtable *rt)
new_rt->rt_gw4 = rt->rt_gw4;
else if (rt->rt_gw_family == AF_INET6)
new_rt->rt_gw6 = rt->rt_gw6;
- INIT_LIST_HEAD(&new_rt->dst.rt_uncached);
new_rt->dst.input = rt->dst.input;
new_rt->dst.output = rt->dst.output;
@@ -2858,8 +2856,6 @@ struct dst_entry *ipv4_blackhole_route(struct net *net, struct dst_entry *dst_or
rt->rt_gw4 = ort->rt_gw4;
else if (rt->rt_gw_family == AF_INET6)
rt->rt_gw6 = ort->rt_gw6;
-
- INIT_LIST_HEAD(&rt->dst.rt_uncached);
}
dst_release(dst_orig);
@@ -91,7 +91,6 @@ static int xfrm4_fill_dst(struct xfrm_dst *xdst, struct net_device *dev,
xdst->u.rt.rt_gw6 = rt->rt_gw6;
xdst->u.rt.rt_pmtu = rt->rt_pmtu;
xdst->u.rt.rt_mtu_locked = rt->rt_mtu_locked;
- INIT_LIST_HEAD(&xdst->u.rt.dst.rt_uncached);
rt_add_uncached_list(&xdst->u.rt);
return 0;
@@ -121,8 +120,7 @@ static void xfrm4_dst_destroy(struct dst_entry *dst)
struct xfrm_dst *xdst = (struct xfrm_dst *)dst;
dst_destroy_metrics_generic(dst);
- if (xdst->u.rt.dst.rt_uncached_list)
- rt_del_uncached_list(&xdst->u.rt);
+ rt_del_uncached_list(&xdst->u.rt);
xfrm_dst_destroy(xdst);
}
@@ -334,7 +334,6 @@ static const struct rt6_info ip6_blk_hole_entry_template = {
static void rt6_info_init(struct rt6_info *rt)
{
memset_after(rt, 0, dst);
- INIT_LIST_HEAD(&rt->dst.rt_uncached);
}
/* allocate dst with ip6_dst_ops */
@@ -89,7 +89,6 @@ static int xfrm6_fill_dst(struct xfrm_dst *xdst, struct net_device *dev,
xdst->u.rt6.rt6i_gateway = rt->rt6i_gateway;
xdst->u.rt6.rt6i_dst = rt->rt6i_dst;
xdst->u.rt6.rt6i_src = rt->rt6i_src;
- INIT_LIST_HEAD(&xdst->u.rt6.dst.rt_uncached);
rt6_uncached_list_add(&xdst->u.rt6);
return 0;
@@ -121,8 +120,7 @@ static void xfrm6_dst_destroy(struct dst_entry *dst)
if (likely(xdst->u.rt6.rt6i_idev))
in6_dev_put(xdst->u.rt6.rt6i_idev);
dst_destroy_metrics_generic(dst);
- if (xdst->u.rt6.dst.rt_uncached_list)
- rt6_uncached_list_del(&xdst->u.rt6);
+ rt6_uncached_list_del(&xdst->u.rt6);
xfrm_dst_destroy(xdst);
}
xfrm_alloc_dst() followed by xfrm4_dst_destroy(), without a xfrm4_fill_dst() call in between, causes the following BUG: BUG: spinlock bad magic on CPU#0, fbxhostapd/732 lock: 0x890b7668, .magic: 890b7668, .owner: <none>/-1, .owner_cpu: 0 CPU: 0 PID: 732 Comm: fbxhostapd Not tainted 6.3.0-rc6-next-20230414-00613-ge8de66369925-dirty #9 Hardware name: Marvell Kirkwood (Flattened Device Tree) unwind_backtrace from show_stack+0x10/0x14 show_stack from dump_stack_lvl+0x28/0x30 dump_stack_lvl from do_raw_spin_lock+0x20/0x80 do_raw_spin_lock from rt_del_uncached_list+0x30/0x64 rt_del_uncached_list from xfrm4_dst_destroy+0x3c/0xbc xfrm4_dst_destroy from dst_destroy+0x5c/0xb0 dst_destroy from rcu_process_callbacks+0xc4/0xec rcu_process_callbacks from __do_softirq+0xb4/0x22c __do_softirq from call_with_stack+0x1c/0x24 call_with_stack from do_softirq+0x60/0x6c do_softirq from __local_bh_enable_ip+0xa0/0xcc Patch "net: dst: Prevent false sharing vs. dst_entry:: __refcnt" moved rt_uncached and rt_uncached_list fields from rtable struct to dst struct, so they are more zeroed by memset_after(xdst, 0, u.dst) in xfrm_alloc_dst(). Note that rt_uncached (list_head) was never properly initialized at alloc time, but xfrm[46]_dst_destroy() is written in such a way that it was not an issue thanks to the memset: if (xdst->u.rt.dst.rt_uncached_list) rt_del_uncached_list(&xdst->u.rt); The route code does it the other way around: rt_uncached_list is assumed to be valid IIF rt_uncached list_head is not empty: void rt_del_uncached_list(struct rtable *rt) { if (!list_empty(&rt->dst.rt_uncached)) { struct uncached_list *ul = rt->dst.rt_uncached_list; spin_lock_bh(&ul->lock); list_del_init(&rt->dst.rt_uncached); spin_unlock_bh(&ul->lock); } } This patch adds mandatory rt_uncached list_head initialization in generic dst_init(), and adapt xfrm[46]_dst_destroy logic to match the rest of the code. Fixes: d288a162dd1c ("net: dst: Prevent false sharing vs. dst_entry:: __refcnt") Reported-by: kernel test robot <oliver.sang@intel.com> Link: https://lore.kernel.org/oe-lkp/202304162125.18b7bcdd-oliver.sang@intel.com Reviewed-by: David Ahern <dsahern@kernel.org> Reviewed-by: Eric Dumazet <edumazet@google.com> CC: Leon Romanovsky <leon@kernel.org> Signed-off-by: Maxime Bizon <mbizon@freebox.fr> --- net/core/dst.c | 1 + net/ipv4/route.c | 4 ---- net/ipv4/xfrm4_policy.c | 4 +--- net/ipv6/route.c | 1 - net/ipv6/xfrm6_policy.c | 4 +--- 5 files changed, 3 insertions(+), 11 deletions(-)