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[82.28.105.188]) by smtp.gmail.com with ESMTPSA id l11sm27199166wrt.54.2020.10.12.10.10.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 12 Oct 2020 10:10:37 -0700 (PDT) From: Alex Dewar Cc: Alex Dewar , John Fastabend , Daniel Borkmann , Jakub Sitnicki , Lorenz Bauer , "David S. Miller" , Jakub Kicinski , Alexei Starovoitov , Martin KaFai Lau , Song Liu , Yonghong Song , Andrii Nakryiko , KP Singh , netdev@vger.kernel.org, bpf@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] net: sockmap: Don't call bpf_prog_put() on NULL pointer Date: Mon, 12 Oct 2020 18:09:53 +0100 Message-Id: <20201012170952.60750-1-alex.dewar90@gmail.com> X-Mailer: git-send-email 2.28.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit To: unlisted-recipients:; (no To-header on input) Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org 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. Addresses-Coverity-ID: 1497799: Null pointer dereferences (FORWARD_NULL) Fixes: 743df8b7749f ("bpf, sockmap: Check skb_verdict and skb_parser programs explicitly") Signed-off-by: Alex Dewar --- 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 df09c39a4dd2..a73ccce54423 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 @@ static int sock_map_link(struct bpf_map *map, struct sk_psock_progs *progs, 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; } -- 2.28.0