From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EA405471434; Tue, 21 Jul 2026 20:22:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784665341; cv=none; b=ftU5XWPkwIbSQ+ACNqFOTxZKJSYnB6Y+PCQgK4FqloibN+4cpWyCCVVH25NZ9BNJqm4Lx7TDqPKvjOipLZjbotmXDWi8QUySUMLburHhTE0E4D+QrEMBrNLxNRcfj79FByGc/Y7+4pXRSm7zOyctKtTss6wLPRZEUETSVcI/G6Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784665341; c=relaxed/simple; bh=1VT9qVhoGsQmm2lABEdkX7fNNlBFa3qfiF6sI1O/Mas=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=F5BVrhmhTg2V8bLO7CJkFc6JwN0LSp4ehnywjewACTsHjxvum+Kq+5jRVnP35FNOSksxESMlhlB80ADXt1j20enWm6YIfz1HfsmY7xjQAojPfxkPHgueFR+Li+BC09jftoIsmOKfZuDReyd0RMMSFyc8VKXBq8Nau3q83zFqCqw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=DR6Mbxj6; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="DR6Mbxj6" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 56DBF1F000E9; Tue, 21 Jul 2026 20:22:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784665339; bh=3xEQtKwznFhAJUaE6gZVy7UMgXgUodfiu4FoxCa+e2I=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=DR6Mbxj6vGZOn2qr5CmAHYOHNXA9xe6/fLJlzCgpGizS1bJDl+tGntOlwz8IbLlJj yFebgFYwDJE0k1G68s5R9izhNCCIpFbgiQTFuZI0X92Lg+M42x3Wkyl4cw+4cRO3bu Jl1pvbdRrgcJIJaBF2IHBlDGeophSd1/USNDp/0Y= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, stable , Maoyi Xie Subject: [PATCH 6.6 0230/1266] usb: gadget: composite: fix dead empty check in the USB_DT_OTG handler Date: Tue, 21 Jul 2026 17:11:07 +0200 Message-ID: <20260721152446.962943628@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152441.786066624@linuxfoundation.org> References: <20260721152441.786066624@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Maoyi Xie commit f8f680609c2b3ab795ffcd6f21585b6dfc46d395 upstream. The OTG branch of composite_setup() falls back to the first configuration when none is selected: if (cdev->config) config = cdev->config; else config = list_first_entry(&cdev->configs, struct usb_configuration, list); if (!config) goto done; ... memcpy(req->buf, config->descriptors[0], value); list_first_entry() never returns NULL. On an empty list it returns container_of() of the list head. So the "if (!config)" check is dead. When cdev->configs is empty, config points at the head inside struct usb_composite_dev. config->descriptors[0] reads whatever sits at that offset. The memcpy copies up to w_length bytes of it into the response buffer. cdev->configs can be empty in two cases. One is a teardown race on gadget unbind with a control transfer in flight. The other is a driver that sets is_otg before it adds a config. A reproducer that holds cdev->configs empty triggers a KASAN fault in this branch. Use list_first_entry_or_null() so the existing check does its job. Fixes: 53e6242db8d6 ("usb: gadget: composite: add USB_DT_OTG request handling") Cc: stable Signed-off-by: Maoyi Xie Link: https://patch.msgid.link/20260527150832.2943293-1-maoyixie.tju@gmail.com Signed-off-by: Greg Kroah-Hartman --- drivers/usb/gadget/composite.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- a/drivers/usb/gadget/composite.c +++ b/drivers/usb/gadget/composite.c @@ -1887,9 +1887,10 @@ composite_setup(struct usb_gadget *gadge if (cdev->config) config = cdev->config; else - config = list_first_entry( + config = list_first_entry_or_null( &cdev->configs, - struct usb_configuration, list); + struct usb_configuration, + list); if (!config) goto done;