From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794049413; b=zhsW1Muq9Y5DWk9dygINmfJvK65/6r+dC11tcJfv0tzPlMRFrL1lnNShZXMfm7EFxEN9 KdPXulJyMVqM0D7uiDh29iL5ha6JhFNKaqp9W0m1ER0q2SUOBH/KFXbbv66QwNLrlcZuc YomGZAMvCnxNFYAXQrjYr2PzItmMmDbcxFirAqIojotQI6BvMwtLRLce6OZCjo9rwmVHU MDbLTKeeRJUorgGz5hkvdTvzNOrn4ABS7IJfvoF39HG0kfotNaFkcBSl0p0nfeBGY7JI4 H0cczs9o4NqQ3C25oF4UCN67c2pTPzLmuyuv/Wy/j+Oml/eYhEdqheTfTqBNURgSv+g== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794049413; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=IKAMh799GV9qjMRac/TdYAywynfWS6DfOzoqpB9m8BU=; b=B+u454SUMYB9ZJqbdJco62IpRdTZvDN2XrTk8IAOYof/Q9OP/1WfiJHOxxZgv9J55mUy gMbyBxwtVrwj1wKZHceU8A34FWCRalomj4tp4YoE0HQnPRQxfKGDE8LeoFpblHu4lREqP wv4DS4vY6VHz3PyeRxhFHXIEgtQN2w68zUaglo5wCn50KwnZWmaHBBv5C93Hj49sX/dYG bQvH9e5kwKMfGvofKYcKD/92ioN2CFj/+VjVOL5luTZ2c1ZmZnNHCg1pxrktH8qBBn9vi SBQ9m7j269notvC4nVjyXcc5BDBuCJopZsv3cAiB/orkFLMrPEBxuWFc3iedn729pfw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b="MQCsm/c1"; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1552E606A326 for ; Sat, 7 Nov 2026 11:03:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=MQCsm/c1 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3F5BE1F0089F; Sat, 7 Nov 2026 11:03:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794049412; bh=IKAMh799GV9qjMRac/TdYAywynfWS6DfOzoqpB9m8BU=; h=From:To:Cc:Subject:Date; b=MQCsm/c1rpqTfvcThPQ8sHHFlllv8of5HMH/x5hwogXZT21+JZ8FMDdn6rjnEmPl6 U+C0MRmbD9OAE2qqzSroeGfhxU5zpM1nFAUyfOWUoSCrJU3AnY9D/9MeXL7hOx51RI dJ7A0VC8f0ivgcFsHpm3zEE+IgW8ywuocfkBVQJZAGwLtLRQJ/l7KjlOtmdoGGSoj7 wLfxxOL6rKvuOkvdvOkvPPCSKJs89Vv6hoCtDlXMpes2RLEnvHpSSX//n4TyyHuAOp retH0ZkjJMjom0uAY4Xn73lIVGx+ShWcWgAqHyaPnD0+H93iVyr/42ryQtJTGtC5Z4 9rWZ/rQjdTSUQ== From: Sasha Levin To: suruurism@gmail.com, jgross@suse.com Cc: stable@vger.kernel.org Subject: FAILED: patch "[PATCH] xen/gntdev: prevent private mappings from becoming writable" failed to apply to 5.15-stable tree Date: Sat, 7 Nov 2026 06:03:31 -0500 Message-ID: <20261107060330-failed-5.15-2176dea8d8c1@kernel.org> X-Mailer: git-send-email 2.53.0 X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x 2176dea8d8c19cb43a9b3651bfa1cb21eab1b31a # git commit -s git send-email --to '' --in-reply-to '20261107060330-failed-5.15-2176dea8d8c1@kernel.org' --subject-prefix 'PATCH 5.15.y' 'HEAD^..' Thanks, Sasha ------------------ original commit in Linus's tree ------------------ >From 2176dea8d8c19cb43a9b3651bfa1cb21eab1b31a Mon Sep 17 00:00:00 2001 From: Abdifatah Suruur Date: Wed, 19 Aug 2026 11:42:17 +0300 Subject: [PATCH] xen/gntdev: prevent private mappings from becoming writable gntdev_mmap() rejects writable private (non-shared) mappings of foreign grant pages, because a private writable mapping takes the COW path on pages that have no proper struct-page backing. However, VM_MAYWRITE is left set, so userspace can map the grant read-only and then upgrade the mapping to writable with mprotect(), hitting the same COW path the check was written to prevent. Clear VM_MAYWRITE for private mappings, as i915 does for its read-only objects and as fixed in drm/vc4 (CVE-2026-68445) and drm/panthor (CVE-2024-53071) and ptp: vmclock (commit a5edadbae57e2298a56cf7a4e774a027905a331f). Fixes: ab31523c2fcac ("xen/gntdev: allow usermode to map granted pages") Cc: stable@vger.kernel.org Signed-off-by: Abdifatah Suruur Reviewed-by: Juergen Gross Signed-off-by: Juergen Gross Message-ID: <20260819084217.1577-1-suruurism@gmail.com> --- drivers/xen/gntdev.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c index 1dcc4675580ed..b71f5bae25b63 100644 --- a/drivers/xen/gntdev.c +++ b/drivers/xen/gntdev.c @@ -1066,6 +1066,13 @@ static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma) if ((vma->vm_flags & VM_WRITE) && !(vma->vm_flags & VM_SHARED)) return -EINVAL; + /* + * Private mappings of foreign grant pages must never become + * writable: they would take the COW path on granted pages. + */ + if (!(vma->vm_flags & VM_SHARED)) + vm_flags_clear(vma, VM_MAYWRITE); + pr_debug("map %d+%d at %lx (pgoff %lx)\n", index, count, vma->vm_start, vma->vm_pgoff); -- 2.53.0