From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-108-mta148.mxroute.com (mail-108-mta148.mxroute.com [136.175.108.148]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 39DB1430CD5 for ; Thu, 8 Oct 2026 20:22:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=136.175.108.148 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791490928; cv=none; b=ZBf0EHfWch2GlVnW2S1fELvbk/Gux+XiB1zMYtCtIGeK7tGXGY7sAcfL7lXkygqF+W940RZnvjNQy6JnOijf7pcXzqIY/tO/kFezlmRFYf/FSH1eT5QgPDi40w1GQTeCZWFGJXzx0K2lnr3oa0I+jkKPoq1vl2vu0wBjMBCyQG0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791490928; c=relaxed/simple; bh=vQ4f+DdSut+dFxep7CZUBeHUCOigx2Bw4utbySVzbfU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=awvGLvWllkwwnpcmWE5cqC8JUZowcdgS8spc9RyBuI8AthA79WzsJG5CHoE2EIhYbdVesVcMnAyRiI1SiBH8zuep3NqOSdbJ3/cHg9+CiZB5KY0/mVtYWxH6Hgv5Vsye4jU5zjmME/IrIE6IG1wUhRgAR8qk8WDC7RSNXMvUa04= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=wii.dev; spf=pass smtp.mailfrom=wii.dev; dkim=pass (2048-bit key) header.d=wii.dev header.i=@wii.dev header.b=dUgZVSE5; arc=none smtp.client-ip=136.175.108.148 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=wii.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=wii.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=wii.dev header.i=@wii.dev header.b="dUgZVSE5" Received: from filter006.mxroute.com ([136.175.111.3] filter006.mxroute.com) (Authenticated sender: mN4UYu2MZsgR) by mail-108-mta148.mxroute.com (ZoneMTA) with ESMTPSA id 1a11d29631800028b2.009 for (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384); Thu, 08 Oct 2026 20:16:54 +0000 X-Zone-Loop: 88435d62da7895400a06480882ad903976ef65946783 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=wii.dev; s=x; h=Content-Transfer-Encoding:MIME-Version:References:In-Reply-To: Message-ID:Date:Subject:Cc:To:From:Sender:Reply-To:Content-Type:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=enDRgdVbSaqltWWaveoCJ8OEHuDYLQQCtusSj0dS0yk=; b=dUgZVSE5dLeN51Q6OErPAl/1q2 AEAnSPZeKCIrdUft2MvCVB6VgvU+OLTVnwEHnZ1r/iH7g4YLiel4xaq5J5LEYGv1hWKmzpCfHR2h6 jlPzWehUWmoj2IkGr7W11twe4Hu4MF/SklGEWSDLgvtroAOpJYewNgorrT71ERw8l+HsKXs+0/eOZ 1903N/xEUAeOJZzXwgINPRKUsReNRBm27CBwK6hicsLDkTg+V6+Y/t+OMp11hJbB0q0J/2/jJ5UAW upVICMlLiiGhJeKmzR+CvSIcqZ1Nn0gyfndVK2OdTwbA8b9ROWa7pnCb5HrbgTkjTYTLGiXSFwWMc opzDVdbg==; From: Richard Patel To: Rick Edgecombe , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org Cc: "H . Peter Anvin" , Kees Cook , Shuah Khan , linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, Richard Patel Subject: [PATCH 1/3] x86/shstk: ban ia32 sigreturn when shadow stack is enabled Date: Thu, 8 Oct 2026 20:16:08 +0000 Message-ID: <20261008201610.1003569-2-ripatel@wii.dev> In-Reply-To: <20261008201610.1003569-1-ripatel@wii.dev> References: <20261008201610.1003569-1-ripatel@wii.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Authenticated-Id: ripatel@wii.dev When returning from a signal via x32 or x64 rt_sigreturn, the shadow-stack-restore token is validated, but ia32 (rt_)sigreturn do not call restore_signal_shadow_stack(). With IA32_EMULATION, 'int $0x80' allows ia32 sigreturn in 64-bit mode, which could defeat sigreturn protection. Refuse ia32 sigreturn by forcing a SIGSEGV instead. Fixes: 05e36022c054 ("x86/shstk: Handle signals for shadow stack") Signed-off-by: Richard Patel --- arch/x86/kernel/signal_32.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/x86/kernel/signal_32.c b/arch/x86/kernel/signal_32.c index 8e87ab586437..a28e750b4e6d 100644 --- a/arch/x86/kernel/signal_32.c +++ b/arch/x86/kernel/signal_32.c @@ -32,6 +32,7 @@ #include #include #include +#include /* * The first GDT descriptor is reserved as 'NULL descriptor'. As bits 0 @@ -109,6 +110,9 @@ static bool ia32_restore_sigcontext(struct pt_regs *regs, { struct sigcontext_32 sc; + if (shstk_is_enabled()) + return false; + /* Always make any pending restarted system calls return -EINTR */ current->restart_block.fn = do_no_restart_syscall; -- 2.52.0