From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E2583C433F5 for ; Thu, 11 Nov 2021 12:22:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B494660FC1 for ; Thu, 11 Nov 2021 12:22:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233225AbhKKMZF (ORCPT ); Thu, 11 Nov 2021 07:25:05 -0500 Received: from Galois.linutronix.de ([193.142.43.55]:49380 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230358AbhKKMZE (ORCPT ); Thu, 11 Nov 2021 07:25:04 -0500 Date: Thu, 11 Nov 2021 12:22:13 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1636633334; 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=vtt68tMQNJUXpzYaWbt0FKFDw0AdSfumZhl982QNQnY=; b=IgVcT3IDfxJnz1QUVE4jFau7np5AkkTtwy23vaToaXXghAF5ZjaYmKW6N2yP2UzSo2Lce1 BGKmmPhV5thc1PaCRXhOHS8QoQ3FLh5r68QW60Ue4Xn1iZS3ctSOtCmmKNbAOnS/M9DqSc lmOZvvYKoGAmB+Z1tc1LVunasejwyV0ITTQ6luYDP7VCUgMMphjaNLGSiR41HVWtSt8QCY TdWYWE0xQcOAzMgfDmNyIoILvWKkQYgY0cmtQHIZ93x5AkAiIHsd8sj0GxO90psStHgDNY phrRFb0gXZpwl8WzVU+wr6EzYYnNuI2f5sve1iyNGNhfv9EI4aOBzsoG0xAAGA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1636633334; 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=vtt68tMQNJUXpzYaWbt0FKFDw0AdSfumZhl982QNQnY=; b=HG3Scmq/yETlEc99NOSChxp+jdFZ5+Uv0JJTR3350i987F7tfCKbn6jsWtT+8nMiW+aClC eZLll8Ey5mVWjqAw== From: "tip-bot2 for Greg Thelen" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: perf/urgent] perf/core: Avoid put_page() when GUP fails Cc: Greg Thelen , "Peter Zijlstra (Intel)" , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20211111021814.757086-1-gthelen@google.com> References: <20211111021814.757086-1-gthelen@google.com> MIME-Version: 1.0 Message-ID: <163663333331.414.639840290224641315.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the perf/urgent branch of tip: Commit-ID: 4716023a8f6a0f4a28047f14dd7ebdc319606b84 Gitweb: https://git.kernel.org/tip/4716023a8f6a0f4a28047f14dd7ebdc319606b84 Author: Greg Thelen AuthorDate: Wed, 10 Nov 2021 18:18:14 -08:00 Committer: Peter Zijlstra CommitterDate: Thu, 11 Nov 2021 13:09:34 +01:00 perf/core: Avoid put_page() when GUP fails PEBS PERF_SAMPLE_PHYS_ADDR events use perf_virt_to_phys() to convert PMU sampled virtual addresses to physical using get_user_page_fast_only() and page_to_phys(). Some get_user_page_fast_only() error cases return false, indicating no page reference, but still initialize the output page pointer with an unreferenced page. In these error cases perf_virt_to_phys() calls put_page(). This causes page reference count underflow, which can lead to unintentional page sharing. Fix perf_virt_to_phys() to only put_page() if get_user_page_fast_only() returns a referenced page. Fixes: fc7ce9c74c3ad ("perf/core, x86: Add PERF_SAMPLE_PHYS_ADDR") Signed-off-by: Greg Thelen Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20211111021814.757086-1-gthelen@google.com --- kernel/events/core.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index f2253ea..523106a 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -7154,7 +7154,6 @@ void perf_output_sample(struct perf_output_handle *handle, static u64 perf_virt_to_phys(u64 virt) { u64 phys_addr = 0; - struct page *p = NULL; if (!virt) return 0; @@ -7173,14 +7172,15 @@ static u64 perf_virt_to_phys(u64 virt) * If failed, leave phys_addr as 0. */ if (current->mm != NULL) { + struct page *p; + pagefault_disable(); - if (get_user_page_fast_only(virt, 0, &p)) + if (get_user_page_fast_only(virt, 0, &p)) { phys_addr = page_to_phys(p) + virt % PAGE_SIZE; + put_page(p); + } pagefault_enable(); } - - if (p) - put_page(p); } return phys_addr;