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 47E3E1A8F94; Thu, 20 Feb 2025 14:06:31 +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=1740060392; cv=none; b=unMqydj/LulESYOddfqj63/ooyal//Nmo7UbUcp30faAJgTgP/vmpIyfr54vCvgLi1CEmBIxOKOmxjnCDkdDcyVgmLUGMW8Z+mb90/2D8wGaXjZ6fivEjAMOas1s1UeHV00HxGfM7Jq8nxIHoO9r3dcW97Trg2MPIPZXyxMtvLo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740060392; c=relaxed/simple; bh=4oo5bwiM+XhKfUR8UYyGQVQWQ/6Ov6wGIKczUKT0zuU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=EAm3ZB5L12/umHboqDi2IKSuOUVC02hExqFtx4T7Kyce992jW+qF8iqE7reJW6+XimuD8NyDSYByePL0Bkla2uZ5q5+6Yket4rZ3c2G60mXaNLsXzY9Ta8aUBpPuT8PIK6aXS6Jop0zHl/cFQXgNc9PMbxUmn6qeEiCzT0EOXDY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=btmol7l+; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="btmol7l+" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2B85BC4CEDD; Thu, 20 Feb 2025 14:06:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1740060391; bh=4oo5bwiM+XhKfUR8UYyGQVQWQ/6Ov6wGIKczUKT0zuU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=btmol7l+E9F0Dq7CHFxzj9ptIoP+WuCKdQeF+u8NmZcIuPkyJT5yDE84M3+w0mGE/ p/2qSrormQ0zOOprtPL8ucuyM3VHc7dHH7VBp0EWNDJDfNSbLCDVQSzYiq5Orhkqic 7RCgsE2BhKYMI1t2f75vNDYQLIB6HMfqUkhwybrk= Date: Thu, 20 Feb 2025 15:06:28 +0100 From: Greg Kroah-Hartman To: =?iso-8859-1?Q?Th=E9o?= Lebrun Cc: "Rafael J. Wysocki" , Danilo Krummrich , Rob Herring , Saravana Kannan , "David S. Miller" , Grant Likely , linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, Liam Girdwood , Mark Brown , Jaroslav Kysela , Takashi Iwai , Binbin Zhou , linux-sound@vger.kernel.org, Vladimir Kondratiev , =?iso-8859-1?Q?Gr=E9gory?= Clement , Thomas Petazzoni , Tawfik Bayouk , stable@vger.kernel.org Subject: Re: [PATCH 0/2] driver core: platform: avoid use-after-free on device name Message-ID: <2025022004-scheming-expend-b9b3@gregkh> References: <20250218-pdev-uaf-v1-0-5ea1a0d3aba0@bootlin.com> <2025022005-affluent-hardcore-c595@gregkh> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Thu, Feb 20, 2025 at 02:31:29PM +0100, Théo Lebrun wrote: > Hello Greg, > > On Thu Feb 20, 2025 at 1:41 PM CET, Greg Kroah-Hartman wrote: > > On Tue, Feb 18, 2025 at 12:00:11PM +0100, Théo Lebrun wrote: > >> The use-after-free bug appears when: > >> - A platform device is created from OF, by of_device_add(); > >> - The same device's name is changed afterwards using dev_set_name(), > >> by its probe for example. > >> > >> Out of the 37 drivers that deal with platform devices and do a > >> dev_set_name() call, only one might be affected. That driver is > >> loongson-i2s-plat [0]. All other dev_set_name() calls are on children > >> devices created on the spot. The issue was found on downstream kernels > >> and we don't have what it takes to test loongson-i2s-plat. > >> > >> Note: loongson-i2s-plat maintainers are CCed. > >> > >> ⟩ # Finding potential trouble-makers: > >> ⟩ git grep -l 'struct platform_device' | xargs grep -l dev_set_name > >> > >> The solution proposed is to add a flag to platform_device that tells if > >> it is responsible for freeing its name. We can then duplicate the > >> device name inside of_device_add() instead of copying the pointer. > > > > Ick. > > > >> What is done elsewhere? > >> - Platform bus code does a copy of the argument name that is stored > >> alongside the struct platform_device; see platform_device_alloc()[1]. > >> - Other busses duplicate the device name; either through a dynamic > >> allocation [2] or through an array embedded inside devices [3]. > >> - Some busses don't have a separate name; when they want a name they > >> take it from the device [4]. > > > > Really ick. > > > > Let's do the right thing here and just get rid of the name pointer > > entirely in struct platform_device please. Isn't that the correct > > thing that way the driver core logic will work properly for all of this. > > I would agree, if it wasn't for this consideration that is found in the > commit message [0]: What, that the of code is broken? Then it should be fixed, why does it need a pointer to a name at all anyway? It shouldn't be needed there either. > > It is important to duplicate! pdev->name must not change to make sure > > the platform_match() return value is stable over time. If we updated > > pdev->name alongside dev->name, once a device probes and changes its > > name then the platform_match() return value would change. > > I'd be fine sending a V2 that removes the field *and the fallback* [1], > but I don't have the full scope in mind to know what would become broken. > > [0]: https://lore.kernel.org/lkml/20250218-pdev-uaf-v1-2-5ea1a0d3aba0@bootlin.com/ > [1]: https://elixir.bootlin.com/linux/v6.13.3/source/drivers/base/platform.c#L1357 The fallback will not need to be removed, properly point to the name of the device and it should work correctly. thanks, greg k-h