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@xxxxxxxxxxxxxx>
---
net/core/sock_map.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/net/core/sock_map.c b/net/core/sock_map.c
index fd8b426dbdf3..f36e13e577a3 100644
--- a/net/core/sock_map.c
+++ b/net/core/sock_map.c
@@ -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);
@@ -873,6 +874,9 @@ 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);
}
--
2.24.1
