From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 20D9CCD98CF for ; Thu, 11 Jun 2026 14:29:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=vilZoDQISoe1jlePuvDDEKBItD7TBlXWXWHI2v7ALUU=; b=DSlprMM0ec422S80EzKHlprE+/ TjSWF1dZ9EoNV1J88TwtAGNMH8wyT72BNuPiY9lroEiWa+qHQv13v3eXGGEXDBzL6zFZVDblX8xJB iV+SVVNWymKpn5WUFHmBB9Agw0Rc2MEXOiBRHQ5dnqwQMgrQb1ZXFKmo6cAwHcIqe2Pq/98zu1joA penZ1u0JtlobD4BnP+NJmawrknGcb79Ki4f0rnOY290j2M3MFLTgcCr8x3q5VjDO9bSHziTYo2Ya6 3YMelC5j8EZAeKRiDMjiGBCUdMH9XouJIRBqj2r02kVKIGWw8AqGXOEbZQoIczmac/TzUVbnObxxp R/KaLZZQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wXgOy-00000009aWi-0r5t; Thu, 11 Jun 2026 14:29:00 +0000 Received: from tor.source.kernel.org ([172.105.4.254]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1wXgOx-00000009aWa-0M49 for kexec@lists.infradead.org; Thu, 11 Jun 2026 14:28:59 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 2C8DB600AA; Thu, 11 Jun 2026 14:28:58 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 754091F00893; Thu, 11 Jun 2026 14:28:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1781188137; bh=vilZoDQISoe1jlePuvDDEKBItD7TBlXWXWHI2v7ALUU=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=IisiybxOoGQs9Wo+hB/KOZUyBLt+NgYjVM4mvhXQBQC17BlI3E/2ywsHXeARxYD+I HWseCM+NPPqlBpteLd+pE9e7Ak2d62iN48+RojGh3QpXhwSQKUPhcqezEgseYge7XX qeoDRsE/9l0+RR+v2C+nekuULwqCcaegZ8eY6+pGTgjUnpl9bQmK/1Ww9qWmwmfVVq ucfNUNGAzSxoxg61LYDYvnFBlylzrwx/zPNBbaS7lzxz1ojen3wJw+jZvJndhAB8ol iDWjS5h3d56vh6cgBswDE7dfXZ2aBkH7eqhtXiQXZx3JS/2niwrFYf+9+8uJ8NCLdT aQ3EUajXXtwZg== Date: Thu, 11 Jun 2026 17:28:50 +0300 From: Mike Rapoport To: Pratyush Yadav Cc: Tarun Sahu , Pasha Tatashin , Andrew Morton , linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-mm@kvack.org Subject: Re: [PATCH] mm/memfd_luo: validate serialized_data before conversion Message-ID: References: <2vxzmrx1qjuf.fsf@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2vxzmrx1qjuf.fsf@kernel.org> X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "kexec" Errors-To: kexec-bounces+kexec=archiver.kernel.org@lists.infradead.org On Thu, Jun 11, 2026 at 03:37:12PM +0200, Pratyush Yadav wrote: > On Thu, Jun 11 2026, Mike Rapoport wrote: > > > On Thu, Jun 11, 2026 at 10:30:03AM +0000, Tarun Sahu wrote: > >> In memfd_luo_finish() and memfd_luo_retrieve(), phys_to_virt() was called > >> on args->serialized_data before checking if the physical address is valid. > >> Since physical address 0 does not map to virtual NULL (due to direct > >> mapping offsets), the subsequent check 'if (!ser)' was ineffective at > >> catching a missing serialized_data, leading to unsafe dereferences later. > >> > >> Validate that args->serialized_data is non-zero before calling > >> phys_to_virt(). > >> > >> Fixes: b3749f174d68 ("mm: memfd_luo: allow preserving memfd") > >> Signed-off-by: Tarun Sahu > >> --- > >> mm/memfd_luo.c | 10 ++++++---- > >> 1 file changed, 6 insertions(+), 4 deletions(-) > >> > >> diff --git a/mm/memfd_luo.c b/mm/memfd_luo.c > >> index 59de210bee5f..10f3983b0060 100644 > >> --- a/mm/memfd_luo.c > >> +++ b/mm/memfd_luo.c > >> @@ -397,10 +397,11 @@ static void memfd_luo_finish(struct liveupdate_file_op_args *args) > >> if (args->retrieve_status) > >> return; > >> > >> - ser = phys_to_virt(args->serialized_data); > >> - if (!ser) > >> + if (!args->serialized_data) > > > > We really should make args->serialized_data a KHOSER_PTR > > Hmm, that would also be a good idea. I suppose then it would be a better > to directly convert to using KHOSER_PTR() instead of this patch? Makes sense. > -- > Regards, > Pratyush Yadav -- Sincerely yours, Mike.