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[2620:137:e000::3:7]) by mx.google.com with ESMTPS id i83-20020a0ddf56000000b005a7d57894a5si1808346ywe.310.2023.10.27.02.57.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 27 Oct 2023 02:57:37 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:7 as permitted sender) client-ip=2620:137:e000::3:7; Authentication-Results: mx.google.com; dkim=pass header.i=@linutronix.de header.s=2020 header.b=C1xmK7ui; dkim=neutral (no key) header.i=@linutronix.de header.s=2020e; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:7 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=linutronix.de Received: from out1.vger.email (depot.vger.email [IPv6:2620:137:e000::3:0]) by snail.vger.email (Postfix) with ESMTP id 01F6382ECB24; Fri, 27 Oct 2023 02:57:36 -0700 (PDT) X-Virus-Status: Clean X-Virus-Scanned: clamav-milter 0.103.10 at snail.vger.email Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345658AbjJ0J5b (ORCPT + 26 others); Fri, 27 Oct 2023 05:57:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60998 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345535AbjJ0J52 (ORCPT ); Fri, 27 Oct 2023 05:57:28 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 656CE9D; Fri, 27 Oct 2023 02:57:26 -0700 (PDT) Date: Fri, 27 Oct 2023 09:57:23 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1698400644; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=9QXnNJdPkKLz3x6SPpOv5gxnlzTrafB+QAcDcSFVjbk=; b=C1xmK7ui4CY0ifg/pkoMHUlFFFDTvIkclp8t/4z5Ew/8T6xtrNMoojFxKBhEhtpbPFqdZr r0VCkGcRe/e7Qi2fUyKf4IwMV9fznJ59+820mM6ft0OvFjH52yC3nmmQR3B/11OndXDE2P KwSQwCI3S9zwNojvj7OViAYbp68fSLHQe5d+Yv8SF4ZaTA9195zQbv8FKSVWg+xR2eUTOj iz8seTCHVGihsh8/BpTDzE2khhIkQWhh1QX7tGu3YRmt1hFFM5WetteXS5EqbHJ2GAvmGT QEUtlrrQLkkVF/7fy4mZtfPrUjg1r31pfbe/ygZcHUOnJpqAhvvlrlzf6iFEBQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1698400644; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=9QXnNJdPkKLz3x6SPpOv5gxnlzTrafB+QAcDcSFVjbk=; b=cwpyQoIYONl9qCZTaN3dW+o64q+PKt+0okWnMPZI8uOFAWTDKZtis1AQONPiGpNVN2EtYk YtjTDeGDUQVG0BDA== From: "tip-bot2 for Ben Wolsieffer" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: locking/core] futex: Don't include process MM in futex key on no-MMU Cc: Ben Wolsieffer , Ingo Molnar , Peter Zijlstra , Thomas Gleixner , Darren Hart , Davidlohr Bueso , andrealmeid@igalia.com, x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20231019204548.1236437-2-ben.wolsieffer@hefring.com> References: <20231019204548.1236437-2-ben.wolsieffer@hefring.com> MIME-Version: 1.0 Message-ID: <169840064334.3135.17333452924302036818.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails X-Spam-Status: No, score=-4.4 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_MED,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (snail.vger.email [0.0.0.0]); Fri, 27 Oct 2023 02:57:36 -0700 (PDT) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1780902167735616832 X-GMAIL-MSGID: 1780902167735616832 The following commit has been merged into the locking/core branch of tip: Commit-ID: c73801ae4f22b390228ebf471d55668e824198b6 Gitweb: https://git.kernel.org/tip/c73801ae4f22b390228ebf471d55668e824198b6 Author: Ben Wolsieffer AuthorDate: Thu, 19 Oct 2023 16:45:49 -04:00 Committer: Ingo Molnar CommitterDate: Fri, 27 Oct 2023 11:53:42 +02:00 futex: Don't include process MM in futex key on no-MMU On no-MMU, all futexes are treated as private because there is no need to map a virtual address to physical to match the futex across processes. This doesn't quite work though, because private futexes include the current process's mm_struct as part of their key. This makes it impossible for one process to wake up a shared futex being waited on in another process. Fix this bug by excluding the mm_struct from the key. With a single address space, the futex address is already a unique key. Fixes: 784bdf3bb694 ("futex: Assume all mappings are private on !MMU systems") Signed-off-by: Ben Wolsieffer Signed-off-by: Ingo Molnar Acked-by: Peter Zijlstra Cc: Thomas Gleixner Cc: Darren Hart Cc: Davidlohr Bueso Cc: André Almeida Link: https://lore.kernel.org/r/20231019204548.1236437-2-ben.wolsieffer@hefring.com --- kernel/futex/core.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/kernel/futex/core.c b/kernel/futex/core.c index ade7c73..52695c5 100644 --- a/kernel/futex/core.c +++ b/kernel/futex/core.c @@ -252,7 +252,17 @@ int get_futex_key(u32 __user *uaddr, unsigned int flags, union futex_key *key, * but access_ok() should be faster than find_vma() */ if (!fshared) { - key->private.mm = mm; + /* + * On no-MMU, shared futexes are treated as private, therefore + * we must not include the current process in the key. Since + * there is only one address space, the address is a unique key + * on its own. + */ + if (IS_ENABLED(CONFIG_MMU)) + key->private.mm = mm; + else + key->private.mm = NULL; + key->private.address = address; return 0; }