From patchwork Tue Jun 17 05:07:11 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kuen-Han Tsai X-Patchwork-Id: 897511 Received: from mail-lj1-f201.google.com (mail-lj1-f201.google.com [209.85.208.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2A60523B63E for ; Tue, 17 Jun 2025 05:08:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.208.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750136932; cv=none; b=pLe8ZkG70+XKLywkadaPmUbF7kp+M+oe0CCK4zto33dU2nUcs2JYEZflN68unNMRNDOls+gWliG+dULgVC6gID77rQtuEsVwhc6gAI3jbADoa2Lm1/Eq0j8IYb5F0THp7Prbf/mybg59Tvw9o8CwdxQB/O2MarE4OigVEjg2Gk8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750136932; c=relaxed/simple; bh=+7dQxfUhGAy4SS1ZpusUklS9/5+phcCn7k7KJyX8YGk=; h=Date:Mime-Version:Message-ID:Subject:From:To:Cc:Content-Type; b=t3As310OA4hWt2gppKqbHGZUv+JOZ2GLN8ihQ1+Np7G3hV3soZZUkhHw3WDRrH4BOfixhQ2D9yX2Hz640R3+1HxzSVuAc7CWpdhJJ/fWV4ux2o0TbaEy8INPg5F9DjtPzc2tbHcJ3LtDR+mgRbER/oa8TA54d7PRm4N7v6AMjCo= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--khtsai.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=QtriyEwb; arc=none smtp.client-ip=209.85.208.201 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--khtsai.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="QtriyEwb" Received: by mail-lj1-f201.google.com with SMTP id 38308e7fff4ca-32b4a06b780so11682701fa.0 for ; Mon, 16 Jun 2025 22:08:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1750136928; x=1750741728; darn=vger.kernel.org; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=i4dXhN7ywt5V6z7FHvJ0Inv2dYG936KTwLKv+c4EnAc=; b=QtriyEwboByUju6vVYF/5SO9P9TVo30yx270KgBvhSwB4IrkQNlaLH/aQqhuBa9UyA n7FkFTpgdrLLWEwGnZLPjtofqNHcUAKEa4GikOlYxi7jFlvF67Rpvvil1kIoL8Y897VN 4KkzMwnU0rcu2TE+h3mX1WRP1OaLXMguKc++S9wWuqC4OYvhcOAFJYm7Wfa5bWNo54Fv Pjs9znkUitRXmbVHfyGDiEeWC/9Bk82eyzJxYUQwPUOqCoe1dmyMRzN4SKWEPvlGo7Bm 8dkrYcbOkvD61RIneuLbrV98CFapRgaFcXevo3SG0ds3dZwi3+aLHNKd5pbgGAgX6fb/ jYAA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1750136928; x=1750741728; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=i4dXhN7ywt5V6z7FHvJ0Inv2dYG936KTwLKv+c4EnAc=; b=evXC4UiFHN53ERA+rEbQx6dMQAIT1aY0dg0RAcRlbMILNZdYLm7YjVnv4jlEyVeCFM 9m1RZoqRNp19wHCqBpNPVxyA2cDCurId3etSnqOA3u43WDf3/Ktaj8cl6s/nTdQy+nRU tWT2MyYRzUw1G7aEAcduhyhzNgCsuALaKcjS4GPwVadMxsYYS4yjZFgeQx5UNJiyveii /x1Ad2NrK3Cq/arbOobJKXwbJD+SMHd54taExUIabhbO0EmWzDwSg7h3BfgeYP6T+540 CKFcqycvRUne8jESY+9/4DpBhTMFwkfp6n3RG5Og81QEPI+oyYhW3yAj1QGnlPtbpw+O Dc7w== X-Gm-Message-State: AOJu0Yzsqj3TLT9HEZ58p0gJ1K7ymHkjgGEHRY4/dGAaJY3YnIMeaHGf y16BlAXn1jVrMD/FgjfE3X+w61CPke16j/0XmIWqbjbBSVgZeTuciRIyv/4w0sjPyaKOL0L5C0I 1SQk7XQ== X-Google-Smtp-Source: AGHT+IH4I8plCvioKdZPJMsYCNlKjSMJlVrKTpGxX4/Kq8vkc4UpNbDk8MhbJk4PV7yT/LvA0ujCcpLOmy4= X-Received: from ljbq21.prod.google.com ([2002:a2e:a015:0:b0:32b:3deb:7b97]) (user=khtsai job=prod-delivery.src-stubby-dispatcher) by 2002:a05:651c:b20:b0:32a:847c:a1c0 with SMTP id 38308e7fff4ca-32b4a0c5893mr29872581fa.6.1750136928270; Mon, 16 Jun 2025 22:08:48 -0700 (PDT) Date: Tue, 17 Jun 2025 13:07:11 +0800 Precedence: bulk X-Mailing-List: linux-usb@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 X-Mailer: git-send-email 2.50.0.rc2.692.g299adb8693-goog Message-ID: <20250617050844.1848232-1-khtsai@google.com> Subject: [PATCH v2 1/2] Revert "usb: gadget: u_serial: Add null pointer check in gs_start_io" From: Kuen-Han Tsai To: gregkh@linuxfoundation.org, prashanth.k@oss.qualcomm.com, khtsai@google.com, hulianqin@vivo.com, krzysztof.kozlowski@linaro.org, mwalle@kernel.org, jirislaby@kernel.org Cc: linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org This reverts commit ffd603f214237e250271162a5b325c6199a65382. Commit ffd603f21423 ("usb: gadget: u_serial: Add null pointer check in gs_start_io") adds null pointer checks at the beginning of the gs_start_io() function to prevent a null pointer dereference. However, these checks are redundant because the function's comment already requires callers to hold the port_lock and ensure port.tty and port_usb are not null. All existing callers already follow these rules. The true cause of the null pointer dereference is a race condition. When gs_start_io() calls either gs_start_rx() or gs_start_tx(), the port_lock is temporarily released for usb_ep_queue(). This allows port.tty and port_usb to be cleared. Fixes: ffd603f21423 ("usb: gadget: u_serial: Add null pointer check in gs_start_io") Signed-off-by: Kuen-Han Tsai --- v2: - Remove Cc: stable --- drivers/usb/gadget/function/u_serial.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) -- 2.50.0.rc2.692.g299adb8693-goog diff --git a/drivers/usb/gadget/function/u_serial.c b/drivers/usb/gadget/function/u_serial.c index ab544f6824be..c043bdc30d8a 100644 --- a/drivers/usb/gadget/function/u_serial.c +++ b/drivers/usb/gadget/function/u_serial.c @@ -544,20 +544,16 @@ static int gs_alloc_requests(struct usb_ep *ep, struct list_head *head, static int gs_start_io(struct gs_port *port) { struct list_head *head = &port->read_pool; - struct usb_ep *ep; + struct usb_ep *ep = port->port_usb->out; int status; unsigned started; - if (!port->port_usb || !port->port.tty) - return -EIO; - /* Allocate RX and TX I/O buffers. We can't easily do this much * earlier (with GFP_KERNEL) because the requests are coupled to * endpoints, as are the packet sizes we'll be using. Different * configurations may use different endpoints with a given port; * and high speed vs full speed changes packet sizes too. */ - ep = port->port_usb->out; status = gs_alloc_requests(ep, head, gs_read_complete, &port->read_allocated); if (status)