From patchwork Mon Jun 3 06:41:22 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Anshuman Khandual X-Patchwork-Id: 10972407 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 0A203933 for ; Mon, 3 Jun 2019 06:42:15 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id EDC3C287FB for ; Mon, 3 Jun 2019 06:42:14 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id CDAFB288A7; Mon, 3 Jun 2019 06:42:14 +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=-5.2 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 72333287FB for ; Mon, 3 Jun 2019 06:42:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:MIME-Version:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:References: In-Reply-To:Message-Id:Date:Subject:To:From:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=YZktyg5sFKWHgxdlQv/IPkZj2IUu86V3T/fl4Z0z9kM=; b=B9ae8NS4/V+/7P7SQAo7tJtA2U Mebtsioj9wddGDmBADJDJXtdvrjO5VqgfGuldFNkf8uSO8VNdbYGuqTrNHnkCA9Hh69QuE1mlBtj1 LR9yCXB1yVjV7vLh62N9eGE/gYbGWiuU9qZHlaETKO6GODYqMfQrLAHO3dmLrKKbB97dCL/IHjaZZ lvO6DKpaVBoYoPdubr2bfg5xfCqQbB34pJrU2baVyur7sC7VxSE069lY+aWgn+0Vpjove82/Txk3J XEeaTKQLnw7OcMeWB5wdbOd6YBP7nZwblTDX0H63fINeCo0HyQcMPSyJ//TPS04aEyqsbO7Ng9LNj 22rHmKHQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1hXgfZ-0001mR-Vy; Mon, 03 Jun 2019 06:42:09 +0000 Received: from foss.arm.com ([217.140.101.70]) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1hXgfT-0001e2-Bq for linux-arm-kernel@lists.infradead.org; Mon, 03 Jun 2019 06:42:06 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 73E9F15AB; Sun, 2 Jun 2019 23:42:02 -0700 (PDT) Received: from p8cg001049571a15.blr.arm.com (p8cg001049571a15.blr.arm.com [10.162.40.144]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 88E193F5AF; Sun, 2 Jun 2019 23:41:59 -0700 (PDT) From: Anshuman Khandual To: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: [PATCH V2 1/4] arm64/mm: Drop mmap_sem before calling __do_kernel_fault() Date: Mon, 3 Jun 2019 12:11:22 +0530 Message-Id: <1559544085-7502-2-git-send-email-anshuman.khandual@arm.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1559544085-7502-1-git-send-email-anshuman.khandual@arm.com> References: <1559544085-7502-1-git-send-email-anshuman.khandual@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190602_234203_682535_B246CA4F X-CRM114-Status: GOOD ( 11.75 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Anshuman Khandual , Catalin Marinas , Will Deacon , James Morse , Andrey Konovalov MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP There is an inconsistency between down_read_trylock() success and failure paths while dealing with kernel access for non exception table areas where it calls __do_kernel_fault(). In case of failure it just bails out without holding mmap_sem but when it succeeds it does so while holding mmap_sem. Fix this inconsistency by just dropping mmap_sem in success path as well. __do_kernel_fault() calls die_kernel_fault() which then calls show_pte(). show_pte() in this path might become bit more unreliable without holding mmap_sem. But there are already instances [1] in do_page_fault() where die_kernel_fault() gets called without holding mmap_sem. show_pte() can be made more robust independently but in a later patch. [1] Conditional block for (is_ttbr0_addr && is_el1_permission_fault) Signed-off-by: Anshuman Khandual Cc: Catalin Marinas Cc: Will Deacon Cc: Mark Rutland Cc: James Morse Cc: Andrey Konovalov --- arch/arm64/mm/fault.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index a30818e..dc1cf32 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -503,8 +503,10 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr, */ might_sleep(); #ifdef CONFIG_DEBUG_VM - if (!user_mode(regs) && !search_exception_tables(regs->pc)) + if (!user_mode(regs) && !search_exception_tables(regs->pc)) { + up_read(&mm->mmap_sem); goto no_context; + } #endif }