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([2405:201:682f:383f:6adb:27a7:d382:d9c9]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-82f8ec24850sm15689255b3a.60.2026.04.21.19.15.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 21 Apr 2026 19:15:41 -0700 (PDT) From: Deepanshu Kartikey To: courmisch@gmail.com, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Deepanshu Kartikey , syzbot+706f5eb79044e686c794@syzkaller.appspotmail.com Subject: [PATCH] net: phonet: fix BUG_ON() in pn_socket_autobind() Date: Wed, 22 Apr 2026 07:45:33 +0530 Message-ID: <20260422021533.16987-1-kartikey406@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit pn_socket_autobind() calls pn_socket_bind() and treats -EINVAL as a signal that the socket was already bound, then uses BUG_ON() to verify it: if (err != -EINVAL) return err; BUG_ON(!pn_port(pn_sk(sock->sk)->sobject)); However, pn_socket_bind() returns -EINVAL in multiple cases: 1. address length too short 2. socket not in TCP_CLOSE state 3. socket already bound <- only intended case When -EINVAL comes from cases 1 or 2, sobject is still zero (never assigned), causing BUG_ON to fire and crash the kernel. Fix this by checking the bound state directly via pn_port(sobject) BEFORE calling pn_socket_bind(), eliminating the ambiguous -EINVAL interpretation entirely. Reported-by: syzbot+706f5eb79044e686c794@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=706f5eb79044e686c794 Signed-off-by: Deepanshu Kartikey --- net/phonet/socket.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/net/phonet/socket.c b/net/phonet/socket.c index c4af26357144..5a55e7d14e85 100644 --- a/net/phonet/socket.c +++ b/net/phonet/socket.c @@ -204,14 +204,14 @@ static int pn_socket_autobind(struct socket *sock) struct sockaddr_pn sa; int err; + if (pn_port(pn_sk(sock->sk)->sobject)) + return 0; /* socket was already bound */ + memset(&sa, 0, sizeof(sa)); sa.spn_family = AF_PHONET; err = pn_socket_bind(sock, (struct sockaddr_unsized *)&sa, sizeof(struct sockaddr_pn)); - if (err != -EINVAL) - return err; - BUG_ON(!pn_port(pn_sk(sock->sk)->sobject)); - return 0; /* socket was already bound */ + return err; } static int pn_socket_connect(struct socket *sock, struct sockaddr_unsized *addr, -- 2.43.0