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 X-Spam-Level: X-Spam-Status: No, score=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B195FC3A5A2 for ; Tue, 3 Sep 2019 16:28:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 887B32343A for ; Tue, 3 Sep 2019 16:28:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1567528117; bh=urNInznHZI2aRo94h5A82g7O8URXJ+rk3UFOBKTyf7k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=W3oR4VTpto/LWGFM97sAs/cw1uy3dY0cppwfvAP6jXCBZHzunlpzr3jezg+FlIkR/ bjTu90mfBA3SnzPrTUzBTarrDD46WMlYVQTPd8btpbCQOIrQNwDCYspWMQ/ciXXV7L hkefrWxPmpv7SCrWfZ598M4bsggUHHuu6RuQUe+0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730156AbfICQ2g (ORCPT ); Tue, 3 Sep 2019 12:28:36 -0400 Received: from mail.kernel.org ([198.145.29.99]:50506 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731138AbfICQ2a (ORCPT ); Tue, 3 Sep 2019 12:28:30 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 8D24B2343A; Tue, 3 Sep 2019 16:28:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1567528109; bh=urNInznHZI2aRo94h5A82g7O8URXJ+rk3UFOBKTyf7k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=phknTkxeux0r/pFTRK9RkCc0i4KEV7GrHTJ11mgewLNUpwYJqyrgX2c+D09flZ69J Lx8L+eLZ2R9lj7RQm0nIceAgtmQB5SkJm4beH8yQpEHb70ZPb8LUEgkwJmXYJbZeDw HIye2i1js9yaZZv8tWLSEGNKBk2aBiLEYntPHnhU= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Eugeniy Paltsev , Vineet Gupta , Sasha Levin , linux-snps-arc@lists.infradead.org Subject: [PATCH AUTOSEL 4.19 113/167] ARC: mm: SIGSEGV userspace trying to access kernel virtual memory Date: Tue, 3 Sep 2019 12:24:25 -0400 Message-Id: <20190903162519.7136-113-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190903162519.7136-1-sashal@kernel.org> References: <20190903162519.7136-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Eugeniy Paltsev [ Upstream commit a8c715b4dd73c26a81a9cc8dc792aa715d8b4bb2 ] As of today if userspace process tries to access a kernel virtual addres (0x7000_0000 to 0x7ffff_ffff) such that a legit kernel mapping already exists, that process hangs instead of being killed with SIGSEGV Fix that by ensuring that do_page_fault() handles kenrel vaddr only if in kernel mode. And given this, we can also simplify the code a bit. Now a vmalloc fault implies kernel mode so its failure (for some reason) can reuse the @no_context label and we can remove @bad_area_nosemaphore. Reproduce user test for original problem: ------------------------>8----------------- #include #include int main(int argc, char *argv[]) { volatile uint32_t temp; temp = *(uint32_t *)(0x70000000); } ------------------------>8----------------- Cc: Signed-off-by: Eugeniy Paltsev Signed-off-by: Vineet Gupta Signed-off-by: Sasha Levin --- arch/arc/mm/fault.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-) diff --git a/arch/arc/mm/fault.c b/arch/arc/mm/fault.c index 535cf18e8bf2c..4e8143de32e70 100644 --- a/arch/arc/mm/fault.c +++ b/arch/arc/mm/fault.c @@ -66,7 +66,7 @@ void do_page_fault(unsigned long address, struct pt_regs *regs) struct vm_area_struct *vma = NULL; struct task_struct *tsk = current; struct mm_struct *mm = tsk->mm; - int si_code = 0; + int si_code = SEGV_MAPERR; int ret; vm_fault_t fault; int write = regs->ecr_cause & ECR_C_PROTV_STORE; /* ST/EX */ @@ -81,16 +81,14 @@ void do_page_fault(unsigned long address, struct pt_regs *regs) * only copy the information from the master page table, * nothing more. */ - if (address >= VMALLOC_START) { + if (address >= VMALLOC_START && !user_mode(regs)) { ret = handle_kernel_vaddr_fault(address); if (unlikely(ret)) - goto bad_area_nosemaphore; + goto no_context; else return; } - si_code = SEGV_MAPERR; - /* * If we're in an interrupt or have no user * context, we must not take the fault.. @@ -198,7 +196,6 @@ void do_page_fault(unsigned long address, struct pt_regs *regs) bad_area: up_read(&mm->mmap_sem); -bad_area_nosemaphore: /* User mode accesses just cause a SIGSEGV */ if (user_mode(regs)) { tsk->thread.fault_address = address; -- 2.20.1