From patchwork Wed Oct 20 17:43:51 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Eric W. Biederman" X-Patchwork-Id: 12572855 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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BEA7DC433F5 for ; Wed, 20 Oct 2021 17:44:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A77CC6128E for ; Wed, 20 Oct 2021 17:44:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231148AbhJTRrL (ORCPT ); Wed, 20 Oct 2021 13:47:11 -0400 Received: from out02.mta.xmission.com ([166.70.13.232]:40460 "EHLO out02.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230464AbhJTRrH (ORCPT ); Wed, 20 Oct 2021 13:47:07 -0400 Received: from in02.mta.xmission.com ([166.70.13.52]:55052) by out02.mta.xmission.com with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.93) (envelope-from ) id 1mdFe0-00GCwM-DG; Wed, 20 Oct 2021 11:44:52 -0600 Received: from ip68-227-160-95.om.om.cox.net ([68.227.160.95]:47894 helo=localhost.localdomain) by in02.mta.xmission.com with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.93) (envelope-from ) id 1mdFdz-001NdN-4w; Wed, 20 Oct 2021 11:44:51 -0600 From: "Eric W. Biederman" To: linux-kernel@vger.kernel.org Cc: linux-arch@vger.kernel.org, Linus Torvalds , Oleg Nesterov , Al Viro , Kees Cook , "Eric W. Biederman" , Thomas Bogendoerfer , Maciej Rozycki , linux-mips@vger.kernel.org Date: Wed, 20 Oct 2021 12:43:51 -0500 Message-Id: <20211020174406.17889-5-ebiederm@xmission.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <87y26nmwkb.fsf@disp2133> References: <87y26nmwkb.fsf@disp2133> MIME-Version: 1.0 X-XM-SPF: eid=1mdFdz-001NdN-4w;;;mid=<20211020174406.17889-5-ebiederm@xmission.com>;;;hst=in02.mta.xmission.com;;;ip=68.227.160.95;;;frm=ebiederm@xmission.com;;;spf=neutral X-XM-AID: U2FsdGVkX18vAFcVjANIu4vDNha2bth++KrviZjJJPY= X-SA-Exim-Connect-IP: 68.227.160.95 X-SA-Exim-Mail-From: ebiederm@xmission.com Subject: [PATCH 05/20] signal/mips: Update (_save|_restore)_fp_context to fail with -EFAULT X-SA-Exim-Version: 4.2.1 (built Sat, 08 Feb 2020 21:53:50 +0000) X-SA-Exim-Scanned: Yes (on in02.mta.xmission.com) Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org When an instruction to save or restore a register from the stack fails in _save_fp_context or _restore_fp_context return with -EFAULT. This change was made to r2300_fpu.S[1] but it looks like it got lost with the introduction of EX2[2]. This is also what the other implementation of _save_fp_context and _restore_fp_context in r4k_fpu.S does, and what is needed for the callers to be able to handle the error. Furthermore calling do_exit(SIGSEGV) from bad_stack is wrong because it does not terminate the entire process it just terminates a single thread. As the changed code was the only caller of arch/mips/kernel/syscall.c:bad_stack remove the problematic and now unused helper function. Cc: Thomas Bogendoerfer Cc: Maciej Rozycki Cc: linux-mips@vger.kernel.org [1] 35938a00ba86 ("MIPS: Fix ISA I FP sigcontext access violation handling") [2] f92722dc4545 ("MIPS: Correct MIPS I FP sigcontext layout") Fixes: f92722dc4545 ("MIPS: Correct MIPS I FP sigcontext layout") Signed-off-by: "Eric W. Biederman" Reviewed-by: Kees Cook Acked-by: Maciej W. Rozycki Acked-by: Thomas Bogendoerfer --- arch/mips/kernel/r2300_fpu.S | 4 ++-- arch/mips/kernel/syscall.c | 9 --------- 2 files changed, 2 insertions(+), 11 deletions(-) diff --git a/arch/mips/kernel/r2300_fpu.S b/arch/mips/kernel/r2300_fpu.S index 12e58053544f..cbf6db98cfb3 100644 --- a/arch/mips/kernel/r2300_fpu.S +++ b/arch/mips/kernel/r2300_fpu.S @@ -29,8 +29,8 @@ #define EX2(a,b) \ 9: a,##b; \ .section __ex_table,"a"; \ - PTR 9b,bad_stack; \ - PTR 9b+4,bad_stack; \ + PTR 9b,fault; \ + PTR 9b+4,fault; \ .previous .set mips1 diff --git a/arch/mips/kernel/syscall.c b/arch/mips/kernel/syscall.c index 2afa3eef486a..5512cd586e6e 100644 --- a/arch/mips/kernel/syscall.c +++ b/arch/mips/kernel/syscall.c @@ -240,12 +240,3 @@ SYSCALL_DEFINE3(cachectl, char *, addr, int, nbytes, int, op) { return -ENOSYS; } - -/* - * If we ever come here the user sp is bad. Zap the process right away. - * Due to the bad stack signaling wouldn't work. - */ -asmlinkage void bad_stack(void) -{ - do_exit(SIGSEGV); -}