From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 F2EAC3DB8F for ; Wed, 15 Nov 2023 20:04:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="2qCJcSPw" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9B20FC433CD; Wed, 15 Nov 2023 20:04:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1700078665; bh=WxeX3xrxNYArzdkonNI6YtB6FyUvqpj0ygKZjH+YFz0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=2qCJcSPwwBtLeYi8xr7aWmwR9lpkp4ndG1UMt1tKtVkZwqI9RXk1xhdnIPehU5aTy j5dGvZgYMCLnzAN8T7feIa1m+gg/1fJVtD4uUBRQj8or+QPWKA8gtiKkqTlr8mqRR3 s8tCEPjROSUc8D05YXn0ozF262CnIR28OYWcpW7M= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Jia-Ju Bai , Sasha Levin Subject: [PATCH 4.14 26/45] usb: dwc2: fix possible NULL pointer dereference caused by driver concurrency Date: Wed, 15 Nov 2023 14:33:03 -0500 Message-ID: <20231115191421.148564705@linuxfoundation.org> X-Mailer: git-send-email 2.42.1 In-Reply-To: <20231115191419.641552204@linuxfoundation.org> References: <20231115191419.641552204@linuxfoundation.org> User-Agent: quilt/0.67 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 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jia-Ju Bai [ Upstream commit ef307bc6ef04e8c1ea843231db58e3afaafa9fa6 ] In _dwc2_hcd_urb_enqueue(), "urb->hcpriv = NULL" is executed without holding the lock "hsotg->lock". In _dwc2_hcd_urb_dequeue(): spin_lock_irqsave(&hsotg->lock, flags); ... if (!urb->hcpriv) { dev_dbg(hsotg->dev, "## urb->hcpriv is NULL ##\n"); goto out; } rc = dwc2_hcd_urb_dequeue(hsotg, urb->hcpriv); // Use urb->hcpriv ... out: spin_unlock_irqrestore(&hsotg->lock, flags); When _dwc2_hcd_urb_enqueue() and _dwc2_hcd_urb_dequeue() are concurrently executed, the NULL check of "urb->hcpriv" can be executed before "urb->hcpriv = NULL". After urb->hcpriv is NULL, it can be used in the function call to dwc2_hcd_urb_dequeue(), which can cause a NULL pointer dereference. This possible bug is found by an experimental static analysis tool developed by myself. This tool analyzes the locking APIs to extract function pairs that can be concurrently executed, and then analyzes the instructions in the paired functions to identify possible concurrency bugs including data races and atomicity violations. The above possible bug is reported, when my tool analyzes the source code of Linux 6.5. To fix this possible bug, "urb->hcpriv = NULL" should be executed with holding the lock "hsotg->lock". After using this patch, my tool never reports the possible bug, with the kernelconfiguration allyesconfig for x86_64. Because I have no associated hardware, I cannot test the patch in runtime testing, and just verify it according to the code logic. Fixes: 33ad261aa62b ("usb: dwc2: host: spinlock urb_enqueue") Signed-off-by: Jia-Ju Bai Link: https://lore.kernel.org/r/20230926024404.832096-1-baijiaju@buaa.edu.cn Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/usb/dwc2/hcd.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/usb/dwc2/hcd.c b/drivers/usb/dwc2/hcd.c index 50ec2cd36db0a..6d2060377dc4a 100644 --- a/drivers/usb/dwc2/hcd.c +++ b/drivers/usb/dwc2/hcd.c @@ -4842,8 +4842,8 @@ static int _dwc2_hcd_urb_enqueue(struct usb_hcd *hcd, struct urb *urb, if (qh_allocated && qh->channel && qh->channel->qh == qh) qh->channel->qh = NULL; fail2: - spin_unlock_irqrestore(&hsotg->lock, flags); urb->hcpriv = NULL; + spin_unlock_irqrestore(&hsotg->lock, flags); kfree(qtd); qtd = NULL; fail1: -- 2.42.0