From patchwork Mon Sep 19 10:44:51 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Rutland X-Patchwork-Id: 9338951 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 566476077A for ; Mon, 19 Sep 2016 10:45:40 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 4175E28B91 for ; Mon, 19 Sep 2016 10:45:40 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 3105829188; Mon, 19 Sep 2016 10:45:40 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.2 required=2.0 tests=BAYES_00, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.wl.linuxfoundation.org (Postfix) with SMTP id AB49028CF2 for ; Mon, 19 Sep 2016 10:45:37 +0000 (UTC) Received: (qmail 18095 invoked by uid 550); 19 Sep 2016 10:45:33 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Reply-To: kernel-hardening@lists.openwall.com Delivered-To: mailing list kernel-hardening@lists.openwall.com Received: (qmail 18059 invoked from network); 19 Sep 2016 10:45:30 -0000 Date: Mon, 19 Sep 2016 11:44:51 +0100 From: Mark Rutland To: Andy Lutomirski , Yoshinori Sato Cc: "linux-arm-kernel@lists.infradead.org" , Andrew Morton , Ard Biesheuvel , Catalin Marinas , james.morse@arm.com, Kees Cook , "linux-kernel@vger.kernel.org" , lorenzo.pieralisi@arm.com, Andrew Lutomirski , suzuki.poulose@arm.com, Takahiro Akashi , Will Deacon , "kernel-hardening@lists.openwall.com" Message-ID: <20160919104254.GA12473@leverpostej> References: <1473947349-14521-1-git-send-email-mark.rutland@arm.com> <1473947349-14521-3-git-send-email-mark.rutland@arm.com> <20160916103101.GA21702@leverpostej> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Subject: [kernel-hardening] Re: [RFC PATCH 2/8] thread_info: allow custom in-task thread_info X-Virus-Scanned: ClamAV using ClamSMTP [Adding Yosinori Sato for h8300] On Fri, Sep 16, 2016 at 08:11:14AM -0700, Andy Lutomirski wrote: > > On Thu, Sep 15, 2016 at 11:37:47AM -0700, Andy Lutomirski wrote: > > > On Thu, Sep 15, 2016 at 6:49 AM, Mark Rutland wrote: > > Just to check, what do you mean to happen with the flags field? Should > > that always be in the generic thread_info? e.g. > > > > struct thread_info { > > u32 flags; > > #ifdef arch_thread_info > > struct arch_thread_info arch_ti; > > #endif > > }; > > Exactly. Possibly with a comment that using thread_struct should be > preferred and that arch_thread_info should be used only if some header > file requires access via current_thread_info() or task_thread_info(). Sure thing. While looking at that, I spotted that would cause a circular include on h8300, but that appears to be because of a larger bug anyhow. It seems h8300 has thread_info::restart_block, and manipulates this in its signal code, yet core code manipulates task_struct::restart_block. I think we need something like the below (which is completely untested). Thanks, Mark. ---->8---- From 4dfbdc7706bfb03a48999ff69e85e0c7361adffe Mon Sep 17 00:00:00 2001 From: Mark Rutland Date: Mon, 19 Sep 2016 11:33:42 +0100 Subject: [PATCH] h8300: fix syscall restarting Back in commit f56141e3e2d9aabf ("all arches, signal: move restart_block to struct task_struct"), all architectures and core code were changed to use task_struct::restart_block. However, when h8300 support was subsequently restored in v4.2, it was not updated to account for this, and maintains thread_info::restart_block, which is not kept in sync. This patch drops the redundant restart_block from thread_info, and moves h8300 to the common one in task_struct, ensuring that syscall restarting always works as expected. Signed-off-by: Mark Rutland Cc: Andy Lutomirski Cc: Yoshinori Sato Cc: stable@vger.kernel.org # v4.2+ --- arch/h8300/include/asm/thread_info.h | 4 ---- arch/h8300/kernel/signal.c | 2 +- 2 files changed, 1 insertion(+), 5 deletions(-) diff --git a/arch/h8300/include/asm/thread_info.h b/arch/h8300/include/asm/thread_info.h index b408fe6..3cef068 100644 --- a/arch/h8300/include/asm/thread_info.h +++ b/arch/h8300/include/asm/thread_info.h @@ -31,7 +31,6 @@ struct thread_info { int cpu; /* cpu we're on */ int preempt_count; /* 0 => preemptable, <0 => BUG */ mm_segment_t addr_limit; - struct restart_block restart_block; }; /* @@ -44,9 +43,6 @@ struct thread_info { .cpu = 0, \ .preempt_count = INIT_PREEMPT_COUNT, \ .addr_limit = KERNEL_DS, \ - .restart_block = { \ - .fn = do_no_restart_syscall, \ - }, \ } #define init_thread_info (init_thread_union.thread_info) diff --git a/arch/h8300/kernel/signal.c b/arch/h8300/kernel/signal.c index ad1f81f..7138303 100644 --- a/arch/h8300/kernel/signal.c +++ b/arch/h8300/kernel/signal.c @@ -79,7 +79,7 @@ restore_sigcontext(struct sigcontext *usc, int *pd0) unsigned int er0; /* Always make any pending restarted system calls return -EINTR */ - current_thread_info()->restart_block.fn = do_no_restart_syscall; + current->restart_block.fn = do_no_restart_syscall; /* restore passed registers */ #define COPY(r) do { err |= get_user(regs->r, &usc->sc_##r); } while (0)