From patchwork Tue Apr 30 11:29:34 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: 10923339 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 51D5B92A for ; Tue, 30 Apr 2019 11:34:18 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 401DE28AAE for ; Tue, 30 Apr 2019 11:34:18 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 2F0BC28AB0; Tue, 30 Apr 2019 11:34:18 +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 2AA4D28AAE for ; Tue, 30 Apr 2019 11:34:16 +0000 (UTC) Received: (qmail 32064 invoked by uid 550); 30 Apr 2019 11:31:36 -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 20373 invoked from network); 30 Apr 2019 11:30:05 -0000 DKIM-Filter: OpenDKIM Filter v2.11.0 terminus.zytor.com x3UBTYcg1350551 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zytor.com; s=2019041745; t=1556623775; bh=tzqP+K1slI+8lkDw9KMmwPxdNB3wF9JoSTcYZ2Gu0vA=; h=Date:From:Cc:Reply-To:In-Reply-To:References:To:Subject:From; b=FwPL4LRMUuEAkydDlPd1E2tmpB2Wz+cFAGQ8iuBCXrf1UHvBTIKRb08kBW2MA7rYe 3hn5medFE5dY3fi/RVgosqJUekt604V5rFP9oICVSj1b0Si70I4r+jNkSGQP6BUcVP K5pNEvPCQgMksBlchjeVH1mvw4qdTBA1FUPBDR9w+vnMVlwEP07z2+jmuiqBdNo+/L c345GsfdV9BBMwy9KXIErqdli6/Yx7SR43xwlTeWrq2jp2rjt5GmdSmwLvHsJiq8Z2 tR61NjmdL9zwouHRUzTNCvHYTugnnCl0OKu3wxPf6p2iQ0e4nVG0rZYqamNinNygmz Uece1pV0p2yrQ== Date: Tue, 30 Apr 2019 04:29:34 -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: ard.biesheuvel@linaro.org, bp@alien8.de, dave.hansen@linux.intel.com, linux_dti@icloud.com, riel@surriel.com, akpm@linux-foundation.org, deneen.t.dock@intel.com, linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, kristen@linux.intel.com, hpa@zytor.com, will.deacon@arm.com, mingo@kernel.org, mhiramat@kernel.org, tglx@linutronix.de, rick.p.edgecombe@intel.com, luto@kernel.org, kernel-hardening@lists.openwall.com, peterz@infradead.org, namit@vmware.com In-Reply-To: <20190426001143.4983-22-namit@vmware.com> References: <20190426001143.4983-22-namit@vmware.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/mm] x86/alternatives: Add comment about module removal races Git-Commit-ID: 3950746d9d8ef981c1cb842384e0e86e8d1aad76 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: 3950746d9d8ef981c1cb842384e0e86e8d1aad76 Gitweb: https://git.kernel.org/tip/3950746d9d8ef981c1cb842384e0e86e8d1aad76 Author: Nadav Amit AuthorDate: Thu, 25 Apr 2019 17:11:41 -0700 Committer: Ingo Molnar CommitDate: Tue, 30 Apr 2019 12:38:01 +0200 x86/alternatives: Add comment about module removal races Add a comment to clarify that users of text_poke() must ensure that no races with module removal take place. 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: Masami Hiramatsu Cc: Rik van Riel Cc: Thomas Gleixner Link: https://lkml.kernel.org/r/20190426001143.4983-22-namit@vmware.com Signed-off-by: Ingo Molnar --- arch/x86/kernel/alternative.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index 18f959975ea0..7b9b49dfc05a 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -810,6 +810,11 @@ static void *__text_poke(void *addr, const void *opcode, size_t len) * It means the size must be writable atomically and the address must be aligned * in a way that permits an atomic write. It also makes sure we fit on a single * page. + * + * Note that the caller must ensure that if the modified code is part of a + * module, the module would not be removed during poking. This can be achieved + * by registering a module notifier, and ordering module removal and patching + * trough a mutex. */ void *text_poke(void *addr, const void *opcode, size_t len) {