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bpf, sockhash: Synchronize_rcu before free'ing map

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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 2bb90e5cc9 ("bpf:
sockmap, synchronize_rcu before free'ing map") which addressed sockmap,
which comes from a manual audit.

Fixes: 604326b41a ("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
This commit is contained in:
Jakub Sitnicki 2020-02-06 12:16:51 +01:00 committed by Daniel Borkmann
parent db6a5018b6
commit 0b2dc83906
1 changed files with 4 additions and 0 deletions
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4
net/core/sock_map.c
View file

@ -250,6 +250,7 @@ static void sock_map_free(struct bpf_map *map)
}
raw_spin_unlock_bh(&stab->lock);
/* wait for psock readers accessing its map link */
synchronize_rcu();
bpf_map_area_free(stab->sks);
@ -877,6 +878,9 @@ static void sock_hash_free(struct bpf_map *map)
raw_spin_unlock_bh(&bucket->lock);
}
/* wait for psock readers accessing its map link */
synchronize_rcu();
bpf_map_area_free(htab->buckets);
kfree(htab);
}