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 D408E2E36F1; Tue, 29 Jul 2025 00:46:48 +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=1753750009; cv=none; b=acFqCXMGVuVFlTRNNYQ+T8nbBMFEaMjfKQXliiUSYDrjPUg5K5Ex0BNNUg9C1T929XMGuMeLDBWpgeokKXzIh7nN1E53Wg8tiTiou/lFexGuWVa4kebZhwCOkcgmI1hzTukhkMDq5lKjq6c0assqA1rWNCZJx25+i6qtie2QlHw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753750009; c=relaxed/simple; bh=bf2RqIM7mDDlK0HjMycdmFAJchzK94V9wrFA7aCHun4=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=fMDc5svjEE4SX06IFCTdUBUi8NLFiHTGs/akM65NJA1ZAzJpwQ8ADC2SrYKFRM0qgGyMXPo8BB1TkFTbNurURzkluMKGMk2LfzzAlvjN7Sp8ca33BzTN6nNKexEBL6mXyb/NZguXJi3bRGdgXWd3aDNJD4wU9q+oc8jkORSb1ao= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=u0eNBzxh; 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="u0eNBzxh" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5C767C4CEE7; Tue, 29 Jul 2025 00:46:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1753750008; bh=bf2RqIM7mDDlK0HjMycdmFAJchzK94V9wrFA7aCHun4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=u0eNBzxhf6u+q2DiutlhwrYKjQQsYsH2s+8rqUsYxrcsthzG+tEf4HVgYKnnGNLaE V6AWlSauqKBBpSVY7BapmpAsWqQvvp7DpRuaMU+09fe9Z6sLgA3Ag/hFujnFAS+K+0 suz4gWnxUrZdbsIkEQFkwyEmTHjGNQUncPWDREsVzdgTF9LAoNsadEN+DCxmQPhwEp 1ETX9k63El46k8kGOZw1JYYPNwvkOCnKW25zhmhMFxanIThPYyT2EyCcCJGxHYvr4c 9gjedV9h6iSB1E+9vaBujYIWNVv85ahgG3RY86/rkNVUDsQgEBnEYzOinB67J83hq+ kobiV9AUIo/mQ== Date: Mon, 28 Jul 2025 17:46:47 -0700 From: Kees Cook To: Hans de Goede Cc: Greg Kroah-Hartman , zepta , Ard Biesheuvel , Andy Shevchenko , Mauro Carvalho Chehab , Sakari Ailus , linux-media@vger.kernel.org, linux-staging@lists.linux.dev, Bartosz Golaszewski , Abraham Samuel Adekunle , Thomas Andreatta , linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: Re: [PATCH] staging: media: atomisp: Fix stack buffer overflow in gmin_get_var_int() Message-ID: <202507281745.0D675898@keescook> References: <20250724080756.work.741-kees@kernel.org> <0b284755-1ae7-4f5f-8338-836dfcb1db59@kernel.org> Precedence: bulk X-Mailing-List: linux-staging@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0b284755-1ae7-4f5f-8338-836dfcb1db59@kernel.org> On Sat, Jul 26, 2025 at 02:24:51PM +0200, Hans de Goede wrote: > Hi Kees, > > On 24-Jul-25 10:08 AM, Kees Cook wrote: > > When gmin_get_config_var() calls efi.get_variable() and the EFI variable > > is larger than the expected buffer size, two behaviors combine to create > > a stack buffer overflow: > > > > 1. gmin_get_config_var() does not return the proper error code when > > efi.get_variable() fails. It returns the stale 'ret' value from > > earlier operations instead of indicating the EFI failure. > > > > 2. When efi.get_variable() returns EFI_BUFFER_TOO_SMALL, it updates > > *out_len to the required buffer size but writes no data to the output > > buffer. However, due to bug #1, gmin_get_var_int() believes the call > > succeeded. > > > > The caller gmin_get_var_int() then performs: > > - Allocates val[CFG_VAR_NAME_MAX + 1] (65 bytes) on stack > > - Calls gmin_get_config_var(dev, is_gmin, var, val, &len) with len=64 > > - If EFI variable is >64 bytes, efi.get_variable() sets len=required_size > > - Due to bug #1, thinks call succeeded with len=required_size > > - Executes val[len] = 0, writing past end of 65-byte stack buffer > > > > This creates a stack buffer overflow when EFI variables are larger than > > 64 bytes. Since EFI variables can be controlled by firmware or system > > configuration, this could potentially be exploited for code execution. > > > > Fix the bug by returning proper error codes from gmin_get_config_var() > > based on EFI status instead of stale 'ret' value. > > > > The gmin_get_var_int() function is called during device initialization > > for camera sensor configuration on Intel Bay Trail and Cherry Trail > > platforms using the atomisp camera stack. > > > > Reported-by: zepta > > Closes: https://lore.kernel.org/all/CAPBS6KoQyM7FMdPwOuXteXsOe44X4H3F8Fw+y_qWq6E+OdmxQA@mail.gmail.com > > Fixes: 38d4f74bc148 ("media: atomisp_gmin_platform: stop abusing efivar API") > > Signed-off-by: Kees Cook > > Thanks, patch looks good to me: > > Reviewed-by: Hans de Goede > > I've already send an atomisp pull-request for 6.17 out > and this is already in media-committers/next now and > the media subsystem is typically not good in merging > fixes just before the merge window. > > Kees, the file touched here is unchanged in > media-committers/next vs Linus' latest master, can you > send this fix to Linus yourself ? I apologize; this slipped through the cracks. Shall I take it for -rc2, or do you want to snag it? -Kees -- Kees Cook