From 0e94d87fcfc81883b72574a5cc4638bd87adbb10 Mon Sep 17 00:00:00 2001 From: John Fastabend Date: Mon, 2 Apr 2018 12:50:52 -0700 Subject: [PATCH] bpf: sockmap, duplicates release calls may NULL sk_prot It is possible to have multiple ULP tcp_release call paths in flight if a sock is closed and simultaneously being removed from the sockmap control path. The result would be setting the sk_prot to the saved values on the first iteration and then on the second iteration setting the value to NULL. This patch resolves this by ensuring we only reset the sk_prot pointer if we have a valid saved state to set. Fixes: 4f738adba30a7 ("bpf: create tcp_bpf_ulp allowing BPF to monitor socket TX/RX data") Signed-off-by: John Fastabend Signed-off-by: Daniel Borkmann --- kernel/bpf/sockmap.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/kernel/bpf/sockmap.c b/kernel/bpf/sockmap.c index 8ddf326..8dd9210 100644 --- a/kernel/bpf/sockmap.c +++ b/kernel/bpf/sockmap.c @@ -182,8 +182,10 @@ static void bpf_tcp_release(struct sock *sk) psock->cork = NULL; } - sk->sk_prot = psock->sk_proto; - psock->sk_proto = NULL; + if (psock->sk_proto) { + sk->sk_prot = psock->sk_proto; + psock->sk_proto = NULL; + } out: rcu_read_unlock(); } -- 2.7.4