From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 0AA5E3ED132; Wed, 20 May 2026 14:43:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779288226; cv=none; b=e9eQZdfrAGhF1MGDzy2arzMEWv31ayrM3SQGcBF1VfeWZ4hEmULgQo7NbzdRTyE6v1yXuyOx6/vbrgrbYk4sB9iusNAAfpRI3/w8p72oG2hTFnSgXQpjuH/HAkmvm7ZTeRqrKGfo1JpduTxaJHHCRChLH+qvKK1RUDNZXkP65EI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779288226; c=relaxed/simple; bh=VZallclgOjr2wEWF4MTjQ7EEFmYD65ALoKpesHf2AK8=; h=Mime-Version:Content-Type:Date:Message-Id:Subject:Cc:To:From: References:In-Reply-To; b=ctBgr2oTBrqVdGBajBS02su8A+IfR44vSvHxYu1iuECzwd2EKhDsT5xk6CQMGQ4IBn8XWdm4VQua61SF8sH0i2lAGaYVV/5CMJy6F6I9XAneGgn9JWSp5149xYKQOa4SYLyArNisQtAybV7kYeGW3DHDItoNNYuok0/1xyfDBwM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=OfuK0N4j; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="OfuK0N4j" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7B2C91F00897; Wed, 20 May 2026 14:43:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1779288224; bh=VZallclgOjr2wEWF4MTjQ7EEFmYD65ALoKpesHf2AK8=; h=Date:Subject:Cc:To:From:References:In-Reply-To; b=OfuK0N4jcGpAq6Ox8yjNQ/rUzJD9HDpU/k32MhvGpAUmoamc2yyw9xmDMyfboNG8e PmaVTVv7QyQa7BGNi0LIzsxTbx2eEMBOttQWiLamXUyP2O13b3xmlkALfNZltZnHzp kLFC6SiyQSO5KcZvEWBAGKE79i7u+N8bfPD+yEK6siKAeFQ5tuJwx3gdTXwdemJmQw LL4L6v5CfATpjx4rPxj0GxYpzReRIAieJb8s+hLEleQmMgJpFm4a5hi23/xF53Bxx+ seAkxmSylCCBIJR4Ku8OhtbQ3elLCa77rUfsjJASAicgFFFOMCY/2AUL6e1nwkT2Ol DGZ5HiqtMbB0A== Precedence: bulk X-Mailing-List: driver-core@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Wed, 20 May 2026 16:43:42 +0200 Message-Id: Subject: Re: [PATCH] sysfs: clamp show() return value in sysfs_kf_read() Cc: , , "Rafael J. Wysocki" , "NeilBrown" , "Tejun Heo" To: "Greg Kroah-Hartman" From: "Danilo Krummrich" References: <2026052000-drove-unicycle-d61b@gregkh> In-Reply-To: <2026052000-drove-unicycle-d61b@gregkh> On Wed May 20, 2026 at 3:07 PM CEST, Greg Kroah-Hartman wrote: > sysfs_kf_seq_show() defends against buggy show() callbacks that return > larger than PAGE_SIZE by clamping the value and printing a warning. > sysfs_kf_read(), the prealloc variant, has no such defense. > > The only current in-tree user of __ATTR_PREALLOC is drivers/md/md.c, > whose show() callbacks are well-behaved, so this is hardening against > future drivers doing foolish things and out-of-tree code doing even more > foolish things. > > Cc: "Rafael J. Wysocki" > Cc: Danilo Krummrich > Cc: NeilBrown > Cc: Tejun Heo > Fixes: 2b75869bba67 ("sysfs/kernfs: allow attributes to request write buf= fer be pre-allocated.") > Assisted-by: gregkh_clanker_t1000 > Signed-off-by: Greg Kroah-Hartman Reviewed-by: Danilo Krummrich