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 4421F823DD; Fri, 26 Sep 2025 16:42:44 +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=1758904965; cv=none; b=NbJOOteZ9ekkIrcl9HB40Zg0i5zOK5VV0EJScUAB3ZKJIlfN0f7vwq0u9IeU4/Q+gz6dFXIqEu9kQT9uQr2yvtcgvsUl5PGbf5J5VPayK8gZHYU+YcymFYtBjse4O1vyDotIZOt5LShOdHqqQn8U7yZQAcZkxr/S/H8kgv/D5Yk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758904965; c=relaxed/simple; bh=EkEGdQzRoQHV/+qgTce+eYgdmMYG6X7KUjwNyIGarvs=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=UlPT6xwXdADAi4TPv8lhrLuUDBrGtTJEc9/lwbqsA1BJNlYZG25nEwYmTo2FE01UMyfXC6H14ZTm99/Ndd1IJAC23iCMzmRHqGfnYgJz3HAtw++hKAt3t4mKi9s9TPk7ZDsAEp4E3rckjZPy2kf3J+XiqcTJurZ0A7H3oZ4FEpI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=jXjCDoU7; 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="jXjCDoU7" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C48F8C4CEF4; Fri, 26 Sep 2025 16:42:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1758904964; bh=EkEGdQzRoQHV/+qgTce+eYgdmMYG6X7KUjwNyIGarvs=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=jXjCDoU7UvglbHeWZlcgdKM51GzyfPYJ50WZcIvbOLT5FgCmiMLvkmFCrrO4aoEAR N7NOisYGIWkXtNetrrSAdLSkg6F2zt6DfYtYNr/WkAduuhS7F005fGtwqKzLQ3CqzC UsJkGx6shKRqXks1NKpSK27vt3p4abdEdL8Z9tLqTUwulM7xEkD8QwPCxmLZLVHgS+ udPJey5RoIhrJXpW5qUbVNZ2yTVt4JuDowuoXEGhOmoqPX3ZOJr+nGUiG71EYLK4UW rVa6y4cBKsruTw5cCfCgqDCAPrETY3n9SkZsf4o0A4sIMXgGXN1uCtSCBl3sOgwnDR TeGph+6DY7wTg== Date: Fri, 26 Sep 2025 17:42:40 +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> 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: 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(). > 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.