From patchwork Tue Apr 30 11:17:18 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: tip-bot for Kobe Wu X-Patchwork-Id: 10923307 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id E7F8892A for ; Tue, 30 Apr 2019 11:30:18 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id D371F28716 for ; Tue, 30 Apr 2019 11:30:18 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id C2DE728751; Tue, 30 Apr 2019 11:30:18 +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=-5.0 required=2.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,MAILING_LIST_MULTI,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 BF4F428716 for ; Tue, 30 Apr 2019 11:30:17 +0000 (UTC) Received: (qmail 7290 invoked by uid 550); 30 Apr 2019 11:28:24 -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: Delivered-To: mailing list kernel-hardening@lists.openwall.com Delivered-To: moderator for kernel-hardening@lists.openwall.com Received: (qmail 11508 invoked from network); 30 Apr 2019 11:17:48 -0000 DKIM-Filter: OpenDKIM Filter v2.11.0 terminus.zytor.com x3UBHIMt1346785 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zytor.com; s=2019041745; t=1556623039; bh=U0dRxSN+YqY2hUrN8UV7cxDakgiQX/5QEsi+3wBp5Ac=; h=Date:From:Cc:Reply-To:In-Reply-To:References:To:Subject:From; b=tiqcCWk5SIYF+VnGYPEiPHdNI39LtMv56xQyq5Y2X6UdgD1kg0BCZO4tcHoiIiTXA fWOSsenbHhzL4c5i5xtAZU2+MXs0A0ZuvEvoH3vazLs/6eKGPBLj0d7KW1ZCwaRrZd aNmk+RT6/gm54+hzu5io2W7oYxO05xcKWDw1ewxzz3XMeetEhaC+00QTddtVuU9F1C Ad6XbFEy4Y4SPhO3W2rH/O/jNPEgkfSLyw6oVjT/LSAt4qxIf/Q42mru3qWCEgkVm6 6W2V9HNHs62WG7MGisd+ZIbG7c4wecW26+0KncG3ekN+7sQ2IXRlpEYOrY5dfZXpVs fE6ufzDIzGBDQ== Date: Tue, 30 Apr 2019 04:17:18 -0700 X-Authentication-Warning: terminus.zytor.com: tipbot set sender to tipbot@zytor.com using -f Sender: tip tree robot From: tip-bot for Nadav Amit Message-ID: Cc: bp@alien8.de, tglx@linutronix.de, hpa@zytor.com, rick.p.edgecombe@intel.com, peterz@infradead.org, mingo@kernel.org, akpm@linux-foundation.org, will.deacon@arm.com, luto@kernel.org, ard.biesheuvel@linaro.org, deneen.t.dock@intel.com, linux-kernel@vger.kernel.org, namit@vmware.com, riel@surriel.com, kristen@linux.intel.com, linux_dti@icloud.com, torvalds@linux-foundation.org, dave.hansen@linux.intel.com, kernel-hardening@lists.openwall.com In-Reply-To: <20190426001143.4983-5-namit@vmware.com> References: <20190426001143.4983-5-namit@vmware.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/mm] x86/mm: Save debug registers when loading a temporary mm Git-Commit-ID: d97080ebed7811a53c931032a284166ee46b9565 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Disposition: inline X-Virus-Scanned: ClamAV using ClamSMTP Commit-ID: d97080ebed7811a53c931032a284166ee46b9565 Gitweb: https://git.kernel.org/tip/d97080ebed7811a53c931032a284166ee46b9565 Author: Nadav Amit AuthorDate: Thu, 25 Apr 2019 17:11:24 -0700 Committer: Ingo Molnar CommitDate: Tue, 30 Apr 2019 12:37:50 +0200 x86/mm: Save debug registers when loading a temporary mm Prevent user watchpoints from mistakenly firing while the temporary mm is being used. As the addresses of the temporary mm might overlap those of the user-process, this is necessary to prevent wrong signals or worse things from happening. Signed-off-by: Nadav Amit Signed-off-by: Rick Edgecombe Signed-off-by: Peter Zijlstra (Intel) Cc: Cc: Cc: Cc: Cc: Cc: Cc: Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Dave Hansen Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Rik van Riel Cc: Thomas Gleixner Link: https://lkml.kernel.org/r/20190426001143.4983-5-namit@vmware.com Signed-off-by: Ingo Molnar --- arch/x86/include/asm/mmu_context.h | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) diff --git a/arch/x86/include/asm/mmu_context.h b/arch/x86/include/asm/mmu_context.h index 24dc3b810970..93dff1963337 100644 --- a/arch/x86/include/asm/mmu_context.h +++ b/arch/x86/include/asm/mmu_context.h @@ -13,6 +13,7 @@ #include #include #include +#include extern atomic64_t last_mm_ctx_id; @@ -380,6 +381,21 @@ static inline temp_mm_state_t use_temporary_mm(struct mm_struct *mm) lockdep_assert_irqs_disabled(); temp_state.mm = this_cpu_read(cpu_tlbstate.loaded_mm); switch_mm_irqs_off(NULL, mm, current); + + /* + * If breakpoints are enabled, disable them while the temporary mm is + * used. Userspace might set up watchpoints on addresses that are used + * in the temporary mm, which would lead to wrong signals being sent or + * crashes. + * + * Note that breakpoints are not disabled selectively, which also causes + * kernel breakpoints (e.g., perf's) to be disabled. This might be + * undesirable, but still seems reasonable as the code that runs in the + * temporary mm should be short. + */ + if (hw_breakpoint_active()) + hw_breakpoint_disable(); + return temp_state; } @@ -387,6 +403,13 @@ static inline void unuse_temporary_mm(temp_mm_state_t prev_state) { lockdep_assert_irqs_disabled(); switch_mm_irqs_off(NULL, prev_state.mm, current); + + /* + * Restore the breakpoints if they were disabled before the temporary mm + * was loaded. + */ + if (hw_breakpoint_active()) + hw_breakpoint_restore(); } #endif /* _ASM_X86_MMU_CONTEXT_H */