From 418a73074da9182f571e467eaded03ea501f3281 Mon Sep 17 00:00:00 2001 From: Maxime Bizon Date: Thu, 20 Apr 2023 20:25:08 +0200 Subject: net: dst: fix missing initialization of rt_uncached 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: /-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 Link: https://lore.kernel.org/oe-lkp/202304162125.18b7bcdd-oliver.sang@intel.com Reviewed-by: David Ahern Reviewed-by: Eric Dumazet CC: Leon Romanovsky Signed-off-by: Maxime Bizon Link: https://lore.kernel.org/r/20230420182508.2417582-1-mbizon@freebox.fr Signed-off-by: Jakub Kicinski --- net/ipv6/xfrm6_policy.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) (limited to 'net/ipv6/xfrm6_policy.c') diff --git a/net/ipv6/xfrm6_policy.c b/net/ipv6/xfrm6_policy.c index 2b493f8d0091..eecc5e59da17 100644 --- a/net/ipv6/xfrm6_policy.c +++ b/net/ipv6/xfrm6_policy.c @@ -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); } -- cgit