From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [213.167.242.64]) (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 38DA817BED0; Mon, 25 Nov 2024 11:33:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.167.242.64 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732534402; cv=none; b=q8iqGeGhA6+d9NNmTaQc3OKYFQrWWQiuELewAyN8cpp4Ni9ay2HxS2zWv0g+ZmqL6VbcYXboCxYXTQjO9ol4oF9amfV6QukQshshKr3g6lgm2ZtWeq4whSSvcZfmP1736EpGR1C+ntY71GF+4oNlap5UTTorRjEqX/KKA6YEeR4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732534402; c=relaxed/simple; bh=P518NXJ0Q6lKfCMBhQpcn8O8iGY86ggsLm0eAR7/Tq8=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=J0dpCFGpp0StWjz3xEGi942d4d9i6QK92trb9DUrkNrirtCTcAeh5O6mOYjWcTl+DPFSZzg6zWLO+jzVH87uX8CG6mbxRAtLs6ftISOZKTpK5x0en8d//bXLhS/lT5L3IrhgWDZht5pGsXcsYvJ5kNTHmhmGMfn/KuGixbfkCkY= ARC-Authentication-Results:i=1; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Hi, On 25/11/2024 10:39, Sakari Ailus wrote: > Hi Cosmin, > > Thanks for the patch. > > On Fri, Nov 22, 2024 at 04:37:12PM +0200, Cosmin Tanislav wrote: >> When using v4l2_subdev_set_routing to set a subdev's routing, and the >> passed routing.num_routes is 0, kmemdup is not called to populate the >> routes of the new routing (which is fine, since we wouldn't want to pass >> a possible NULL value to kmemdup). >> >> This results in subdev's routing.routes to be NULL. >> >> routing.routes is further used in some places without being guarded by >> the same num_routes non-zero condition. >> >> Fix it. > > While I think moving the code to copy the routing table seems reasonable, > is there a need to make num_routes == 0 a special case? No memcpy() > implementation should access destination or source if the size is 0. I think so too, but Cosmin convinced me that the spec says otherwise. From the C spec I have, in "7.21.1 String function conventions": " Where an argument declared as size_t n specifies the length of the array for a function, n can have the value zero on a call to that function. Unless explicitly stated otherwise in the description of a particular function in this subclause, pointer arguments on such a call shall still have valid values, as described in 7.1.4. " The memcpy section has no explicit mention that would hint otherwise. In 7.1.4 Use of library functions it says that unless explicitly stated otherwise, a null pointer is an invalid value. That said, I would still consider memcpy() with size 0 always ok, regardless of the src or dst, as the only memcpy implementation we need to care about is the kernel's. Tomi