From 7aa8ca17655f084b0dcd3d96c81a1e3459d36dbd Mon Sep 17 00:00:00 2001 From: Michal Luczaj Date: Mon, 2 Dec 2024 12:29:23 +0100 Subject: [PATCH] bpf, sockmap: Fix update element with same Consider a sockmap entry being updated with the same socket: osk = stab->sks[idx]; sock_map_add_link(psock, link, map, &stab->sks[idx]); stab->sks[idx] = sk; if (osk) sock_map_unref(osk, &stab->sks[idx]); Due to sock_map_unref(), which invokes sock_map_del_link(), all the psock's links for stab->sks[idx] are torn: list_for_each_entry_safe(link, tmp, &psock->link, list) { if (link->link_raw == link_raw) { ... list_del(&link->list); sk_psock_free_link(link); } } And that includes the new link sock_map_add_link() added just before the unref. This results in a sockmap holding a socket, but without the respective link. This in turn means that close(sock) won't trigger the cleanup, i.e. a closed socket will not be automatically removed from the sockmap. Stop tearing the links when a matching link_raw is found. Signed-off-by: Michal Luczaj --- net/core/sock_map.c | 1 + 1 file changed, 1 insertion(+) diff --git a/net/core/sock_map.c b/net/core/sock_map.c index 78347d7d25ef3..20b348b1964a1 100644 --- a/net/core/sock_map.c +++ b/net/core/sock_map.c @@ -159,6 +159,7 @@ static void sock_map_del_link(struct sock *sk, verdict_stop = true; list_del(&link->list); sk_psock_free_link(link); + break; } } spin_unlock_bh(&psock->link_lock);