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 64AEC2F1FC8; Mon, 29 Sep 2025 09:59:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759139986; cv=none; b=iw/P5BO+5wJWPrBCisBLLaWpls3Xd7GPSn9cfNgpd2FBY0hUg3D58XWLTfEuOE2FWICgfaS8or8rtcqvnIXGpMxD+6pnA7EezaJ0/dQmgOKpGaXvwiDnMLUMpbmloxrlZ8QQdEYJyIIlkeHR1nQ5+d8GHNGn/INmoVffi5eHRj8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759139986; c=relaxed/simple; bh=DagTvSp+7YAi/LuUfSuuyOhuhMMN85uMrXt9yNyDwXg=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=dAneaCyzAvSAWUlRr9WtN6mH2GZbZ8QV8OwbZgxnF9rLGcuLgwWGBtox6OsojbgKvZK6cQgPEMzhWM98zdBKWMyNKhJvoYr+XL5Eg4i8IEf0AJHB7BC1PGWWz7TgjoV/UXmkHo1tln8K6+9XLgfH8WlIgxS50PBP/exNU1lpTpU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=DFkX9Y9L; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="DFkX9Y9L" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0A624C4CEF4; Mon, 29 Sep 2025 09:59:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1759139986; bh=DagTvSp+7YAi/LuUfSuuyOhuhMMN85uMrXt9yNyDwXg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=DFkX9Y9LmfhlZIsnhFCcBpQYWmHlN1hgAkA65NoJ3iTOFffL1Ksn+Z1wDxHLViegX QT94NEK4623YNH9tvzBP+SxfTveBPGx23MKdVdFUfrlRaCAqmIFSNZ2f7qEG8iKg8J GFifAnAKMBvrEgBy8pO1V7oOi7Q7CUe2EJhv6wipIH9Fpdi2OPfvvbCl6HIrgd0fUd WC744hLtq89xwhKChBHzJOPTlKsziojJywxf3ELq9AyzP7PP8l2Aw8JOZ4CX944aYx wbtuLfKkkfqmxa46WVFUnHgPzESiKLzCt1Kj8/1RdfV7r3RVI8OIXFQ5NU+cTuO44T t3CVC6fdKceZw== Date: Mon, 29 Sep 2025 10:59:42 +0100 From: Simon Horman To: Siddharth Vadapalli Cc: Nishanth Menon , Uwe =?utf-8?Q?Kleine-K=C3=B6nig?= , Paolo Abeni , Jakub Kicinski , Eric Dumazet , "David S. Miller" , Andrew Lunn , linux-kernel@vger.kernel.org, netdev@vger.kernel.org Subject: Re: [PATCH] net: netcp: Fix crash in error path when DMA channel open fails Message-ID: References: <20250926150853.2907028-1-nm@ti.com> <08a13fb0-dd12-491e-98af-ef67d55cc403@ti.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <08a13fb0-dd12-491e-98af-ef67d55cc403@ti.com> On Fri, Sep 26, 2025 at 10:28:47PM +0530, Siddharth Vadapalli wrote: > 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. No problem. These error paths are tricking things. > > > 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? I'm ambivalent regarding the dev_err() part. Because the error is always the same. And I'm not really sure that logging it adds anything. But if you do go that way, please consider using %pe. consider using Regarding knav_dma_open_channel(0 always returning NULL, yes, that is my suggestion. Of course the callers and anything else that uses that return value need to be audited and updated as appropriate. Thanks!