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net: decrease cached dst counters in dst_release

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Upstream fix ac888d5886 ("net: do not delay dst_entries_add() in
dst_release()") moved decrementing the dst count from dst_destroy to
dst_release to avoid accessing already freed data in case of netns
dismantle. However in case CONFIG_DST_CACHE is enabled and OvS+tunnels
are used, this fix is incomplete as the same issue will be seen for
cached dsts:

  Unable to handle kernel paging request at virtual address ffff5aabf6b5c000
  Call trace:
   percpu_counter_add_batch+0x3c/0x160 (P)
   dst_release+0xec/0x108
   dst_cache_destroy+0x68/0xd8
   dst_destroy+0x13c/0x168
   dst_destroy_rcu+0x1c/0xb0
   rcu_do_batch+0x18c/0x7d0
   rcu_core+0x174/0x378
   rcu_core_si+0x18/0x30

Fix this by invalidating the cache, and thus decrementing cached dst
counters, in dst_release too.

Fixes: d71785ffc7 ("net: add dst_cache to ovs vxlan lwtunnel")
Signed-off-by: Antoine Tenart <atenart@kernel.org>
Link: https://patch.msgid.link/20250326173634.31096-1-atenart@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Antoine Tenart 2025-03-26 18:36:32 +01:00 • committed by Paolo Abeni
parent 8930424777
commit 3a0a3ff659
1 changed files with 8 additions and 0 deletions
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8
net/core/dst.c
View file

@ -165,6 +165,14 @@ static void dst_count_dec(struct dst_entry *dst)
void dst_release(struct dst_entry *dst)
{
if (dst && rcuref_put(&dst->__rcuref)) {
#ifdef CONFIG_DST_CACHE
if (dst->flags & DST_METADATA) {
struct metadata_dst *md_dst = (struct metadata_dst *)dst;
if (md_dst->type == METADATA_IP_TUNNEL)
dst_cache_reset_now(&md_dst->u.tun_info.dst_cache);
}
#endif
dst_count_dec(dst);
call_rcu_hurry(&dst->rcu_head, dst_destroy_rcu);
}