From 83c11c17553c0fca217105c17444c4ef5ab2403f Mon Sep 17 00:00:00 2001 From: Alex Dewar Date: Mon, 12 Oct 2020 18:09:53 +0100 Subject: [PATCH] net, sockmap: Don't call bpf_prog_put() on NULL pointer If bpf_prog_inc_not_zero() fails for skb_parser, then bpf_prog_put() is called unconditionally on skb_verdict, even though it may be NULL. Fix and tidy up error path. Fixes: 743df8b7749f ("bpf, sockmap: Check skb_verdict and skb_parser programs explicitly") Addresses-Coverity-ID: 1497799: Null pointer dereferences (FORWARD_NULL) Signed-off-by: Alex Dewar Signed-off-by: Daniel Borkmann Acked-by: Jakub Sitnicki Acked-by: John Fastabend Link: https://lore.kernel.org/bpf/20201012170952.60750-1-alex.dewar90@gmail.com --- net/core/sock_map.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) diff --git a/net/core/sock_map.c b/net/core/sock_map.c index 203900a6ca5f..ddc899e83313 100644 --- a/net/core/sock_map.c +++ b/net/core/sock_map.c @@ -238,17 +238,18 @@ static int sock_map_link(struct bpf_map *map, struct sk_psock_progs *progs, int ret; skb_verdict = READ_ONCE(progs->skb_verdict); - skb_parser = READ_ONCE(progs->skb_parser); if (skb_verdict) { skb_verdict = bpf_prog_inc_not_zero(skb_verdict); if (IS_ERR(skb_verdict)) return PTR_ERR(skb_verdict); } + + skb_parser = READ_ONCE(progs->skb_parser); if (skb_parser) { skb_parser = bpf_prog_inc_not_zero(skb_parser); if (IS_ERR(skb_parser)) { - bpf_prog_put(skb_verdict); - return PTR_ERR(skb_parser); + ret = PTR_ERR(skb_parser); + goto out_put_skb_verdict; } } @@ -257,7 +258,7 @@ static int sock_map_link(struct bpf_map *map, struct sk_psock_progs *progs, msg_parser = bpf_prog_inc_not_zero(msg_parser); if (IS_ERR(msg_parser)) { ret = PTR_ERR(msg_parser); - goto out; + goto out_put_skb_parser; } } @@ -311,11 +312,12 @@ out_drop: out_progs: if (msg_parser) bpf_prog_put(msg_parser); -out: - if (skb_verdict) - bpf_prog_put(skb_verdict); +out_put_skb_parser: if (skb_parser) bpf_prog_put(skb_parser); +out_put_skb_verdict: + if (skb_verdict) + bpf_prog_put(skb_verdict); return ret; }