diff mbox series

[5.4,23/96] bpf, sockhash: Synchronize_rcu before freeing map

Message ID 20200213151848.153137952@linuxfoundation.org
State New
Headers show
Series None | expand

Commit Message

Greg Kroah-Hartman Feb. 13, 2020, 3:20 p.m. UTC 
From: Jakub Sitnicki <jakub@cloudflare.com>

commit 0b2dc83906cf1e694e48003eae5df8fa63f76fd9 upstream.

We need to have a synchronize_rcu before free'ing the sockhash because any
outstanding psock references will have a pointer to the map and when they
use it, this could trigger a use after free.

This is a sister fix for sockhash, following commit 2bb90e5cc90e ("bpf:
sockmap, synchronize_rcu before free'ing map") which addressed sockmap,
which comes from a manual audit.

Fixes: 604326b41a6fb ("bpf, sockmap: convert to generic sk_msg interface")
Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200206111652.694507-3-jakub@cloudflare.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 net/core/sock_map.c |    4 ++++
 1 file changed, 4 insertions(+)
diff mbox series

Patch

--- a/net/core/sock_map.c
+++ b/net/core/sock_map.c
@@ -250,6 +250,7 @@  static void sock_map_free(struct bpf_map
 	}
 	raw_spin_unlock_bh(&stab->lock);
 
+	/* wait for psock readers accessing its map link */
 	synchronize_rcu();
 
 	bpf_map_area_free(stab->sks);
@@ -873,6 +874,9 @@  static void sock_hash_free(struct bpf_ma
 		raw_spin_unlock_bh(&bucket->lock);
 	}
 
+	/* wait for psock readers accessing its map link */
+	synchronize_rcu();
+
 	bpf_map_area_free(htab->buckets);
 	kfree(htab);
 }