From nobody Mon Feb 9 12:25:29 2026 Received: from mx0b-00069f02.pphosted.com (mx0b-00069f02.pphosted.com [205.220.177.32]) (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 3270613F431 for ; Thu, 6 Jun 2024 22:40:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=205.220.177.32 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717713659; cv=none; b=eZda6AFt9gfskoacBupNzeQofpVRWBRDnubKHN/pcDFq5rkDCd3AXgbG3/HqQawHj7f9nysqZ38NLaZZ7fNOPakl2G5dtL0NGGo63JddnrmHCbZ3xZ9MD4Ykp5aXn2Wiy77hrRRFinL9TNFMI9HBRVF9f32RmFFf9khDypa1Zh4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717713659; c=relaxed/simple; bh=tlwUG6i2dN04+SFgN9SBdBQln0TBzFDCm4yq8WOlNIQ=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=rAOso2EEkRWsGBPZZJI9O345kMSRQiM3EmIHve5wkMkJcJq1ZCsiZNj+lXQloBM3VPQurv+S+//4ksCCmrdI7KH+BuHIbR1jiKec2VeifXYn7RjqJFiQnLtQGWlngGkWLYvK5b1wVUfqnGBMlkVDF7ynU4LwEbSNPgqSHBCOK0E= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=oracle.com; spf=pass smtp.mailfrom=oracle.com; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b=lv9R9vtf; arc=none smtp.client-ip=205.220.177.32 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=oracle.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=oracle.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="lv9R9vtf" Received: from pps.filterd (m0246632.ppops.net [127.0.0.1]) by mx0b-00069f02.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 456HwrvD029555; Thu, 6 Jun 2024 22:40:43 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=cc : content-transfer-encoding : date : from : in-reply-to : message-id : mime-version : references : subject : to; s=corp-2023-11-20; bh=KPsMX+2z7i40hslxQGSb/YJgYDxUNOarNeZ/dlWFyIc=; b=lv9R9vtf4PrVJbv/A/lqDxDFM932jXBknMLYbftFm1vZy0KD2UeENkAh0o42UwxR8+Cn CCOueNZStC3PgG0JKn/nuiMQJDfm2U7Uiiu21sckr9AtQUh6n40Da6lDt5tVvRTOFhyX In4v1ahl9SCOzeeFDMzYKadARbsJkOj75DVZF+xaNngTKxEwcebHMGMvFtvpO0xSwwaT 96fdZYKVIzyMNBU28eVVhV85PGF7mN7/me+I2d5P60qrQn6aJd4+KLp8bLLMlS8Dlhq3 EMIGBkEUaPjxtGDLDBXUJTfv9zLh3IuAN1vwRSNlWsEUdWTNpYBhul57gg3u4V7cHmyI Bw== Received: from phxpaimrmta01.imrmtpd1.prodappphxaev1.oraclevcn.com (phxpaimrmta01.appoci.oracle.com [138.1.114.2]) by mx0b-00069f02.pphosted.com (PPS) with ESMTPS id 3yjbrscfm4-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 06 Jun 2024 22:40:42 +0000 Received: from pps.filterd (phxpaimrmta01.imrmtpd1.prodappphxaev1.oraclevcn.com [127.0.0.1]) by phxpaimrmta01.imrmtpd1.prodappphxaev1.oraclevcn.com (8.17.1.19/8.17.1.19) with ESMTP id 456LpGRI005543; Thu, 6 Jun 2024 22:40:42 GMT Received: from pps.reinject (localhost [127.0.0.1]) by phxpaimrmta01.imrmtpd1.prodappphxaev1.oraclevcn.com (PPS) with ESMTPS id 3ygrmh5amc-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 06 Jun 2024 22:40:42 +0000 Received: from phxpaimrmta01.imrmtpd1.prodappphxaev1.oraclevcn.com (phxpaimrmta01.imrmtpd1.prodappphxaev1.oraclevcn.com [127.0.0.1]) by pps.reinject (8.17.1.5/8.17.1.5) with ESMTP id 456MebVS028229; Thu, 6 Jun 2024 22:40:41 GMT Received: from aruramak-dev.osdevelopmeniad.oraclevcn.com (aruramak-dev.allregionaliads.osdevelopmeniad.oraclevcn.com [100.100.253.155]) by phxpaimrmta01.imrmtpd1.prodappphxaev1.oraclevcn.com (PPS) with ESMTP id 3ygrmh5ag4-5; Thu, 06 Jun 2024 22:40:41 +0000 From: Aruna Ramakrishna To: linux-kernel@vger.kernel.org Cc: x86@kernel.org, dave.hansen@linux.intel.com, tglx@linutronix.de, mingo@kernel.org, keith.lucas@oracle.com, aruna.ramakrishna@oracle.com Subject: [PATCH v5 4/5] x86/pkeys: Restore altstack before sigcontext Date: Thu, 6 Jun 2024 22:40:34 +0000 Message-Id: <20240606224035.3238985-5-aruna.ramakrishna@oracle.com> X-Mailer: git-send-email 2.39.3 In-Reply-To: <20240606224035.3238985-1-aruna.ramakrishna@oracle.com> References: <20240606224035.3238985-1-aruna.ramakrishna@oracle.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1039,Hydra:6.0.680,FMLib:17.12.28.16 definitions=2024-06-06_18,2024-06-06_02,2024-05-17_01 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 bulkscore=0 mlxscore=0 malwarescore=0 suspectscore=0 spamscore=0 mlxlogscore=724 adultscore=0 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2405010000 definitions=main-2406060156 X-Proofpoint-ORIG-GUID: YRa2sy84gLMLgHKQLd7NICrMSXVH8ooM X-Proofpoint-GUID: YRa2sy84gLMLgHKQLd7NICrMSXVH8ooM Content-Type: text/plain; charset="utf-8" A process can disable access to the alternate signal stack and still expect signals to be delivered correctly. handle_signal() updates the PKRU value to enable access to the atlstack, and makes sure that the value on the sigframe is the user-defined PKRU value so that it is correctly restored. However, in sigreturn(), restore_altstack() needs read access to the alt stack. But the PKRU is already restored from the sigframe (in restore_sigcontext()) which will disable access to the alt stack, resulting in a SIGSEGV. Fix this by restoring altstack before restoring PKRU. Signed-off-by: Aruna Ramakrishna --- arch/x86/kernel/signal_32.c | 4 ++-- arch/x86/kernel/signal_64.c | 6 +++--- 2 files changed, 5 insertions(+), 5 deletions(-) diff --git a/arch/x86/kernel/signal_32.c b/arch/x86/kernel/signal_32.c index 68f2bfd7d6e7..c7a489f0d943 100644 --- a/arch/x86/kernel/signal_32.c +++ b/arch/x86/kernel/signal_32.c @@ -160,10 +160,10 @@ SYSCALL32_DEFINE0(rt_sigreturn) =20 set_current_blocked(&set); =20 - if (!ia32_restore_sigcontext(regs, &frame->uc.uc_mcontext)) + if (restore_altstack32(&frame->uc.uc_stack)) goto badframe; =20 - if (restore_altstack32(&frame->uc.uc_stack)) + if (!ia32_restore_sigcontext(regs, &frame->uc.uc_mcontext)) goto badframe; =20 return regs->ax; diff --git a/arch/x86/kernel/signal_64.c b/arch/x86/kernel/signal_64.c index 6b189de005b5..2d053333fcf5 100644 --- a/arch/x86/kernel/signal_64.c +++ b/arch/x86/kernel/signal_64.c @@ -260,13 +260,13 @@ SYSCALL_DEFINE0(rt_sigreturn) =20 set_current_blocked(&set); =20 - if (!restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags)) + if (restore_altstack(&frame->uc.uc_stack)) goto badframe; =20 - if (restore_signal_shadow_stack()) + if (!restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags)) goto badframe; =20 - if (restore_altstack(&frame->uc.uc_stack)) + if (restore_signal_shadow_stack()) goto badframe; =20 return regs->ax; --=20 2.39.3