From nobody Thu Dec 18 11:46:26 2025 Received: from szxga06-in.huawei.com (szxga06-in.huawei.com [45.249.212.32]) (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 904151DF751; Wed, 12 Feb 2025 08:05:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.32 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739347507; cv=none; b=N2l6grbVAUmRoyfQR8LpgT3nSWIxpDaNkLbHXd6tLWC7CtY2umOLE6o1Qs8azfKuWLgB8nWOwB/t9U71KpeJd/VTLGkMGyEYGOj5uo+SMYslmHF/myKpEmEmh9aWamlPVXu02mO3CNzB06GsjacG3wzZPehQm7S+ennptQXx8X4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739347507; c=relaxed/simple; bh=EtkqaO4zBNpebP2SemeA/84KgY/u+we+cSwF4JjZSAo=; h=From:To:CC:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=aZU6YFLMSJ7f21Z/TTYGoihJpNpwpIbzmKqOb41Pvs+7ggVKJtLdlZjmNSRDZL9+YFesPQHnbHT1irumWZ7SZB+KhxYfe7i1hM3CamuH2Y5VRQqjKq8ShAIv/YQAVX4AqVlsv33xG2vy+mZGxOdRw+Q5kWTMhKYI+c3V7a2w3rU= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=45.249.212.32 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.19.163.17]) by szxga06-in.huawei.com (SkyGuard) with ESMTP id 4Yt9py3ckMz20qK9; Wed, 12 Feb 2025 16:05:30 +0800 (CST) Received: from kwepemg100016.china.huawei.com (unknown [7.202.181.57]) by mail.maildlp.com (Postfix) with ESMTPS id 1540E1A0188; Wed, 12 Feb 2025 16:05:01 +0800 (CST) Received: from huawei.com (10.67.174.33) by kwepemg100016.china.huawei.com (7.202.181.57) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Wed, 12 Feb 2025 16:05:00 +0800 From: GONG Ruiqi To: Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Vlastimil Babka , Kees Cook CC: Tamas Koczka , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, Xiu Jianfeng , , , , Subject: [PATCH v3 2/2] slab: Achieve better kmalloc caches randomization in kvmalloc Date: Wed, 12 Feb 2025 16:15:05 +0800 Message-ID: <20250212081505.2025320-3-gongruiqi1@huawei.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20250212081505.2025320-1-gongruiqi1@huawei.com> References: <20250212081505.2025320-1-gongruiqi1@huawei.com> 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-Transfer-Encoding: quoted-printable X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To kwepemg100016.china.huawei.com (7.202.181.57) As revealed by this writeup[1], due to the fact that __kmalloc_node (now renamed to __kmalloc_node_noprof) is an exported symbol and will never get inlined, using it in kvmalloc_node (now is __kvmalloc_node_noprof) would make the RET_IP inside always point to the same address: upper_caller kvmalloc kvmalloc_node kvmalloc_node_noprof __kvmalloc_node_noprof <-- all macros all the way down here __kmalloc_node_noprof __do_kmalloc_node(.., _RET_IP_) ... <-- _RET_IP_ points to That literally means all kmalloc invoked via kvmalloc would use the same seed for cache randomization (CONFIG_RANDOM_KMALLOC_CACHES), which makes this hardening non-functional. The root cause of this problem, IMHO, is that using RET_IP only cannot identify the actual allocation site in case of kmalloc being called inside non-inlined wrappers or helper functions. And I believe there could be similar cases in other functions. Nevertheless, I haven't thought of any good solution for this. So for now let's solve this specific case first. For __kvmalloc_node_noprof, replace __kmalloc_node_noprof and call __do_kmalloc_node directly instead, so that RET_IP can take the return address of kvmalloc and differentiate each kvmalloc invocation: upper_caller kvmalloc kvmalloc_node kvmalloc_node_noprof __kvmalloc_node_noprof <-- all macros all the way down here __do_kmalloc_node(.., _RET_IP_) ... <-- _RET_IP_ points to Thanks to Tam=C3=A1s Koczka for the report and discussion! Link: https://github.com/google/security-research/blob/908d59b573960dc0b90a= dda6f16f7017aca08609/pocs/linux/kernelctf/CVE-2024-27397_mitigation/docs/ex= ploit.md?plain=3D1#L259 [1] Reported-by: Tam=C3=A1s Koczka Signed-off-by: GONG Ruiqi --- mm/slub.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index abc982d68feb..1f7d1d260eeb 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -4925,9 +4925,9 @@ void *__kvmalloc_node_noprof(DECL_BUCKET_PARAMS(size,= b), gfp_t flags, int node) * It doesn't really make sense to fallback to vmalloc for sub page * requests */ - ret =3D __kmalloc_node_noprof(PASS_BUCKET_PARAMS(size, b), - kmalloc_gfp_adjust(flags, size), - node); + ret =3D __do_kmalloc_node(size, PASS_BUCKET_PARAM(b), + kmalloc_gfp_adjust(flags, size), + node, _RET_IP_); if (ret || size <=3D PAGE_SIZE) return ret; =20 --=20 2.25.1