From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 5EA4513B2B4; Tue, 27 Feb 2024 14:24:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709043898; cv=none; b=hzn/C5i4tSEw72YF3EV4z3yfQRGnteCbISDZ0VF8zei/5TkYuYA64IV2W+bIBgn5UJ5pFpIuy1bK44RIMOt0tPo9EHfUst5zjqYZMmTlg1kehrMbn9CoH9Cwgdo2OW8tfPSBjsTcEy85W93TSPMB/dpxXXr2mC49BuzN3R15kGc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709043898; c=relaxed/simple; bh=YzJs7HZwww/GDAAEpObUi44Vt0iUuksHfWn7zeUyHZA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=GcfGx3zQIkexNsJqUm0K8rI0DtVw1Rl1UBlfNxaAuHrXNEKgg41g4S9chmCCPS8DuICvcGB8Gse4zRljSpZyfvMsFCouNq8N/ARJneEK/vqd10mpvXC97non95oaCIS0Xjk7b5jIFXqq0dp3mjqvQGeDz0apggmRg0wzg5SCkcE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=0oQ+jCCZ; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="0oQ+jCCZ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 90486C433F1; Tue, 27 Feb 2024 14:24:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1709043897; bh=YzJs7HZwww/GDAAEpObUi44Vt0iUuksHfWn7zeUyHZA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=0oQ+jCCZ0aAqXgZ5HhZdXilZ32mZHnOZShmcBRQ3El/elO3UBg7MSUPX9ropIsWfo /h/GSdThySpjJGobOjwqJGZxY855L5WndlWRDurJ9dMOd59sWXJzZ/xWSJwUEWMA6T AW1Wm3Ip91b+rYEivnvsew83Be0QlntCw4xxecIk= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Fei Yang , "Kirill A. Shutemov" , Ingo Molnar , "Peter Zijlstra (Intel)" , Linus Torvalds , Sasha Levin Subject: [PATCH 5.4 46/84] x86/alternatives: Disable KASAN in apply_alternatives() Date: Tue, 27 Feb 2024 14:27:13 +0100 Message-ID: <20240227131554.369226302@linuxfoundation.org> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20240227131552.864701583@linuxfoundation.org> References: <20240227131552.864701583@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Kirill A. Shutemov [ Upstream commit d35652a5fc9944784f6f50a5c979518ff8dacf61 ] Fei has reported that KASAN triggers during apply_alternatives() on a 5-level paging machine: BUG: KASAN: out-of-bounds in rcu_is_watching() Read of size 4 at addr ff110003ee6419a0 by task swapper/0/0 ... __asan_load4() rcu_is_watching() trace_hardirqs_on() text_poke_early() apply_alternatives() ... On machines with 5-level paging, cpu_feature_enabled(X86_FEATURE_LA57) gets patched. It includes KASAN code, where KASAN_SHADOW_START depends on __VIRTUAL_MASK_SHIFT, which is defined with cpu_feature_enabled(). KASAN gets confused when apply_alternatives() patches the KASAN_SHADOW_START users. A test patch that makes KASAN_SHADOW_START static, by replacing __VIRTUAL_MASK_SHIFT with 56, works around the issue. Fix it for real by disabling KASAN while the kernel is patching alternatives. [ mingo: updated the changelog ] Fixes: 6657fca06e3f ("x86/mm: Allow to boot without LA57 if CONFIG_X86_5LEVEL=y") Reported-by: Fei Yang Signed-off-by: Kirill A. Shutemov Signed-off-by: Ingo Molnar Acked-by: Peter Zijlstra (Intel) Cc: Linus Torvalds Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20231012100424.1456-1-kirill.shutemov@linux.intel.com Signed-off-by: Sasha Levin --- arch/x86/kernel/alternative.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index 15bad8d598949..faae8a1856709 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -374,6 +374,17 @@ void __init_or_module noinline apply_alternatives(struct alt_instr *start, u8 insn_buff[MAX_PATCH_LEN]; DPRINTK("alt table %px, -> %px", start, end); + + /* + * In the case CONFIG_X86_5LEVEL=y, KASAN_SHADOW_START is defined using + * cpu_feature_enabled(X86_FEATURE_LA57) and is therefore patched here. + * During the process, KASAN becomes confused seeing partial LA57 + * conversion and triggers a false-positive out-of-bound report. + * + * Disable KASAN until the patching is complete. + */ + kasan_disable_current(); + /* * The scan order should be from start to end. A later scanned * alternative code can overwrite previously scanned alternative code. @@ -434,6 +445,8 @@ void __init_or_module noinline apply_alternatives(struct alt_instr *start, text_poke_early(instr, insn_buff, insn_buff_sz); } + + kasan_enable_current(); } #ifdef CONFIG_SMP -- 2.43.0