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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 30BD7ECAAD2 for ; Mon, 29 Aug 2022 11:48:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230157AbiH2Lsz (ORCPT ); Mon, 29 Aug 2022 07:48:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40770 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230470AbiH2Lse (ORCPT ); Mon, 29 Aug 2022 07:48:34 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3B49889917; Mon, 29 Aug 2022 04:32:01 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id BB09FB80FAF; Mon, 29 Aug 2022 11:17:59 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 037ABC433D6; Mon, 29 Aug 2022 11:17:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1661771878; bh=sqwZwaMa4ltO+ZnF2OW0LOrSQsC+7lCx8oJFCuGBDEU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Ap5TsoJVg8esKzgaj8QhfERta/RmrVncpaM/J5g9OQr1bQ0BWr6J2P0SPthP++BfY 11rZSmxNsZYp4IZcI/NxsdIH9f02/pDv6DjDjz2vTrXUaaIWWnbQMQH8J+0dUHBrjY FLYHgy74qgqPnhWX4FcI12Wg7ZhE7Fu9fODWjmoY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Rustam Subkhankulov , Juergen Gross , Jan Beulich , Oleksandr Tyshchenko Subject: [PATCH 5.19 128/158] xen/privcmd: fix error exit of privcmd_ioctl_dm_op() Date: Mon, 29 Aug 2022 12:59:38 +0200 Message-Id: <20220829105814.449509146@linuxfoundation.org> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220829105808.828227973@linuxfoundation.org> References: <20220829105808.828227973@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Juergen Gross commit c5deb27895e017a0267de0a20d140ad5fcc55a54 upstream. The error exit of privcmd_ioctl_dm_op() is calling unlock_pages() potentially with pages being NULL, leading to a NULL dereference. Additionally lock_pages() doesn't check for pin_user_pages_fast() having been completely successful, resulting in potentially not locking all pages into memory. This could result in sporadic failures when using the related memory in user mode. Fix all of that by calling unlock_pages() always with the real number of pinned pages, which will be zero in case pages being NULL, and by checking the number of pages pinned by pin_user_pages_fast() matching the expected number of pages. Cc: Fixes: ab520be8cd5d ("xen/privcmd: Add IOCTL_PRIVCMD_DM_OP") Reported-by: Rustam Subkhankulov Signed-off-by: Juergen Gross Reviewed-by: Jan Beulich Reviewed-by: Oleksandr Tyshchenko Link: https://lore.kernel.org/r/20220825141918.3581-1-jgross@suse.com Signed-off-by: Juergen Gross Signed-off-by: Greg Kroah-Hartman --- drivers/xen/privcmd.c | 21 +++++++++++---------- 1 file changed, 11 insertions(+), 10 deletions(-) --- a/drivers/xen/privcmd.c +++ b/drivers/xen/privcmd.c @@ -581,27 +581,30 @@ static int lock_pages( struct privcmd_dm_op_buf kbufs[], unsigned int num, struct page *pages[], unsigned int nr_pages, unsigned int *pinned) { - unsigned int i; + unsigned int i, off = 0; - for (i = 0; i < num; i++) { + for (i = 0; i < num; ) { unsigned int requested; int page_count; requested = DIV_ROUND_UP( offset_in_page(kbufs[i].uptr) + kbufs[i].size, - PAGE_SIZE); + PAGE_SIZE) - off; if (requested > nr_pages) return -ENOSPC; page_count = pin_user_pages_fast( - (unsigned long) kbufs[i].uptr, + (unsigned long)kbufs[i].uptr + off * PAGE_SIZE, requested, FOLL_WRITE, pages); - if (page_count < 0) - return page_count; + if (page_count <= 0) + return page_count ? : -EFAULT; *pinned += page_count; nr_pages -= page_count; pages += page_count; + + off = (requested == page_count) ? 0 : off + page_count; + i += !off; } return 0; @@ -677,10 +680,8 @@ static long privcmd_ioctl_dm_op(struct f } rc = lock_pages(kbufs, kdata.num, pages, nr_pages, &pinned); - if (rc < 0) { - nr_pages = pinned; + if (rc < 0) goto out; - } for (i = 0; i < kdata.num; i++) { set_xen_guest_handle(xbufs[i].h, kbufs[i].uptr); @@ -692,7 +693,7 @@ static long privcmd_ioctl_dm_op(struct f xen_preemptible_hcall_end(); out: - unlock_pages(pages, nr_pages); + unlock_pages(pages, pinned); kfree(xbufs); kfree(pages); kfree(kbufs);