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 70345C4332F for ; Mon, 3 Oct 2022 07:17:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230141AbiJCHRt (ORCPT ); Mon, 3 Oct 2022 03:17:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48024 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229986AbiJCHRH (ORCPT ); Mon, 3 Oct 2022 03:17:07 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 554524686D; Mon, 3 Oct 2022 00:14:01 -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 dfw.source.kernel.org (Postfix) with ESMTPS id D4AF160F9B; Mon, 3 Oct 2022 07:14:00 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E88CCC433C1; Mon, 3 Oct 2022 07:13:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1664781240; bh=oKI7NKRGrfksCR9P5ES2xz6H45saQiR1p4Qbpz+75vI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=18KUM+xOYNNDD2kax8P2vT2JH4BteYNlNoPCyafiBbOaDf5mQ4muDMqK1OOvnZnQF eSW+E9rd8XEMQ5JfJzVO0x2FbGM6DcUssVeOHMTO/sdBvjNaNVGZfggaAdfLgelk4M +E/ZBEwpuCV9/zMoEVwx7boJbfgeP1Cz80TBfZNo= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Kees Cook , Yu Zhao , Florian Lehner , Andrew Morton , "Peter Zijlstra (Intel)" , Matthew Wilcox , Josh Poimboeuf , Dave Hansen Subject: [PATCH 5.19 021/101] x86/uaccess: avoid check_object_size() in copy_from_user_nmi() Date: Mon, 3 Oct 2022 09:10:17 +0200 Message-Id: <20221003070725.020436093@linuxfoundation.org> X-Mailer: git-send-email 2.37.3 In-Reply-To: <20221003070724.490989164@linuxfoundation.org> References: <20221003070724.490989164@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: Kees Cook commit 59298997df89e19aad426d4ae0a7e5037074da5a upstream. The check_object_size() helper under CONFIG_HARDENED_USERCOPY is designed to skip any checks where the length is known at compile time as a reasonable heuristic to avoid "likely known-good" cases. However, it can only do this when the copy_*_user() helpers are, themselves, inline too. Using find_vmap_area() requires taking a spinlock. The check_object_size() helper can call find_vmap_area() when the destination is in vmap memory. If show_regs() is called in interrupt context, it will attempt a call to copy_from_user_nmi(), which may call check_object_size() and then find_vmap_area(). If something in normal context happens to be in the middle of calling find_vmap_area() (with the spinlock held), the interrupt handler will hang forever. The copy_from_user_nmi() call is actually being called with a fixed-size length, so check_object_size() should never have been called in the first place. Given the narrow constraints, just replace the __copy_from_user_inatomic() call with an open-coded version that calls only into the sanitizers and not check_object_size(), followed by a call to raw_copy_from_user(). [akpm@linux-foundation.org: no instrument_copy_from_user() in my tree...] Link: https://lkml.kernel.org/r/20220919201648.2250764-1-keescook@chromium.org Link: https://lore.kernel.org/all/CAOUHufaPshtKrTWOz7T7QFYUNVGFm0JBjvM700Nhf9qEL9b3EQ@mail.gmail.com Fixes: 0aef499f3172 ("mm/usercopy: Detect vmalloc overruns") Signed-off-by: Kees Cook Reported-by: Yu Zhao Reported-by: Florian Lehner Suggested-by: Andrew Morton Acked-by: Peter Zijlstra (Intel) Tested-by: Florian Lehner Cc: Matthew Wilcox Cc: Josh Poimboeuf Cc: Dave Hansen Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman --- arch/x86/lib/usercopy.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/lib/usercopy.c b/arch/x86/lib/usercopy.c index ad0139d25401..f1bb18617156 100644 --- a/arch/x86/lib/usercopy.c +++ b/arch/x86/lib/usercopy.c @@ -44,7 +44,7 @@ copy_from_user_nmi(void *to, const void __user *from, unsigned long n) * called from other contexts. */ pagefault_disable(); - ret = __copy_from_user_inatomic(to, from, n); + ret = raw_copy_from_user(to, from, n); pagefault_enable(); return ret; -- 2.37.3