From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lelvem-ot01.ext.ti.com (lelvem-ot01.ext.ti.com [198.47.23.234]) (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 8BCC730597F; Fri, 26 Sep 2025 16:59:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.47.23.234 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758905944; cv=none; b=Yr8fkLGha7rT3QW33QAjr3UhDAPoC1Q4NcziFFSbUAISUYVycV2DMKrx2poeQNN/RWq2UsMAiQfHuhI2fNqqcLe8yQA2Yh3MIgY0hATuja4iczmUDPW64SQTxUcAzdtlYeYSHPfz+5FE9EELNbOSlrDFyOBXPUABu0+ZYtMfjIQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758905944; c=relaxed/simple; bh=Nv1y1fToKCLS5D56SGWW3Fu02+TSW9GRhBBGCOoj1CY=; h=Message-ID:Date:MIME-Version:Subject:To:CC:References:From: In-Reply-To:Content-Type; b=L21c4xznzSwn8GBal+LEJ4pV8mLybURe7prtjrRzIba9W+jll5q8JWzPkLhQ/nAdCEKGrVD81Vcu1K8smFwnGISg2tCdy0Yvg/LGM+SJorZE5CF6VJrRXBqd+mSlSrnSUVAhOlwVZ0TrGQcRvtfwJwH5OgkZYc/nXuNfOfPm6Gk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=ti.com; spf=pass smtp.mailfrom=ti.com; dkim=pass (1024-bit key) header.d=ti.com header.i=@ti.com header.b=zPmry0cB; arc=none smtp.client-ip=198.47.23.234 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=ti.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=ti.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=ti.com header.i=@ti.com header.b="zPmry0cB" Received: from lelvem-sh01.itg.ti.com ([10.180.77.71]) by lelvem-ot01.ext.ti.com (8.15.2/8.15.2) with ESMTP id 58QGwqoq1724430; Fri, 26 Sep 2025 11:58:52 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ti.com; s=ti-com-17Q1; t=1758905932; bh=I+fvoCdpVjcpW6UNDPo2u0wUq3wToFlQcHSjQljHVmc=; h=Date:Subject:To:CC:References:From:In-Reply-To; b=zPmry0cBQUeAHT8RLuJArVnm2ZntV5ECbGa/ln5JQhEw3Zz9drcNLP3yK/M2hZvTp FBk+5XfIN6xTdvygI6Y0dZ6jZM8c7tYLxvpO8vVxmfdnGz2LLMGYb2jSFZj6BBMToc xHhzpbs46h779CU+nnRpAJvjEgvKW/Fqd5HefI28= Received: from DLEE107.ent.ti.com (dlee107.ent.ti.com [157.170.170.37]) by lelvem-sh01.itg.ti.com (8.18.1/8.18.1) with ESMTPS id 58QGwq3q3562496 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-SHA256 bits=128 verify=FAIL); Fri, 26 Sep 2025 11:58:52 -0500 Received: from DLEE208.ent.ti.com (157.170.170.97) by DLEE107.ent.ti.com (157.170.170.37) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2507.55; Fri, 26 Sep 2025 11:58:52 -0500 Received: from lelvem-mr05.itg.ti.com (10.180.75.9) by DLEE208.ent.ti.com (157.170.170.97) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.20 via Frontend Transport; Fri, 26 Sep 2025 11:58:52 -0500 Received: from [10.249.139.123] ([10.249.139.123]) by lelvem-mr05.itg.ti.com (8.18.1/8.18.1) with ESMTP id 58QGwm3w1617584; Fri, 26 Sep 2025 11:58:48 -0500 Message-ID: <08a13fb0-dd12-491e-98af-ef67d55cc403@ti.com> Date: Fri, 26 Sep 2025 22:28:47 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] net: netcp: Fix crash in error path when DMA channel open fails To: Simon Horman CC: Nishanth Menon , =?UTF-8?Q?Uwe_Kleine-K=C3=B6nig?= , Paolo Abeni , Jakub Kicinski , Eric Dumazet , "David S. Miller" , Andrew Lunn , , , References: <20250926150853.2907028-1-nm@ti.com> Content-Language: en-US From: Siddharth Vadapalli In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-C2ProcessedOrg: 333ef613-75bf-4e12-a4b1-8e3623f5dcea On 26/09/25 10:12 PM, Simon Horman wrote: > On Fri, Sep 26, 2025 at 09:57:02PM +0530, Siddharth Vadapalli wrote: >> On 26/09/25 9:43 PM, Simon Horman wrote: >>> On Fri, Sep 26, 2025 at 10:08:53AM -0500, Nishanth Menon wrote: >>>> When knav_dma_open_channel() fails in netcp_setup_navigator_resources(), >>>> the rx_channel field is set to an ERR_PTR value. Later, when >>>> netcp_free_navigator_resources() is called in the error path, it attempts >>>> to close this invalid channel pointer, causing a crash. >>>> >>>> Add a check for ERR values to handle the failure scenario. >>>> >>>> Fixes: 84640e27f230 ("net: netcp: Add Keystone NetCP core driver") >>>> Signed-off-by: Nishanth Menon >>>> --- >>>> >>>> Seen on kci log for k2hk: https://dashboard.kernelci.org/log-viewer?itemId=ti%3A2eb55ed935eb42c292e02f59&org=ti&type=test&url=http%3A%2F%2Ffiles.kernelci.org%2F%2Fti%2Fmainline%2Fmaster%2Fv6.17-rc7-59-gbf40f4b87761%2Farm%2Fmulti_v7_defconfig%2BCONFIG_EFI%3Dy%2BCONFIG_ARM_LPAE%3Dy%2Bdebug%2Bkselftest%2Btinyconfig%2Fgcc-12%2Fbaseline-nfs-boot.nfs-k2hk-evm.txt.gz >>>> >>>> drivers/net/ethernet/ti/netcp_core.c | 2 +- >>>> 1 file changed, 1 insertion(+), 1 deletion(-) >>>> >>>> diff --git a/drivers/net/ethernet/ti/netcp_core.c b/drivers/net/ethernet/ti/netcp_core.c >>>> index 857820657bac..4ff17fd6caae 100644 >>>> --- a/drivers/net/ethernet/ti/netcp_core.c >>>> +++ b/drivers/net/ethernet/ti/netcp_core.c >>>> @@ -1549,7 +1549,7 @@ static void netcp_free_navigator_resources(struct netcp_intf *netcp) >>>> { >>>> int i; >>>> - if (netcp->rx_channel) { >>>> + if (!IS_ERR(netcp->rx_channel)) { >>>> knav_dma_close_channel(netcp->rx_channel); >>>> netcp->rx_channel = NULL; >>>> } >>> >>> Hi Nishanth, >>> >>> Thanks for your patch. >>> >>> I expect that netcp_txpipe_close() has a similar problem too. >>> >>> But I also think that using IS_ERR is not correct, because it seems to me >>> that there are also cases where rx_channel can be NULL. >> >> Could you please clarify where rx_channel is NULL? rx_channel is set by >> invoking knav_dma_open_channel(). > > Hi Siddharth, > > I am assuming that when netcp_setup_navigator_resources() is called, at > least for the first time, that netcp->rx_channel is NULL. So any of the > occurrence of 'goto fail' in that function before the call to > knav_dma_open_channel(). I missed this. Thank you for pointing this out. > >> Also, please refer to: >> https://github.com/torvalds/linux/commit/5b6cb43b4d62 >> which specifically points out that knav_dma_open_channel() will not return >> NULL so the check for NULL isn't required. >>> >>> I see that on error knav_dma_open_channel() always returns ERR_PTR(-EINVAL) >>> (open coded as (void *)-EINVAL) on error. So I think a better approach >>> would be to change knav_dma_open_channel() to return NULL, and update callers >>> accordingly. >> >> The commit referred to above made changes to the driver specifically due to >> the observation that knav_dma_open_channel() never returns NULL. Modifying >> knav_dma_open_channel() to return NULL will effectively result in having to >> undo the changes made by the commit. > > I wasn't aware of that patch. But my observation is that the return value > of knav_dma_open_channel() is still not handled correctly. E.g. the bug > your patch is fixing. And I'm proposing an alternate approach which I feel > will be less error-prone. Ok. If I understand correctly, you are proposing that the 'error codes' returned by knav_dma_open_channel() should be turned into a dev_err() print for the user and knav_dma_open_channel() should always return NULL in case of failure and a pointer to the channel in case of success. Is that right?