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 X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLACK autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 27CDAC433E3 for ; Sat, 15 Aug 2020 00:31:17 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id DCAC722CBE for ; Sat, 15 Aug 2020 00:31:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="b4wgoM9t" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DCAC722CBE Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 836786B006E; Fri, 14 Aug 2020 20:31:16 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 7C1146B0070; Fri, 14 Aug 2020 20:31:16 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 6DB7B6B0071; Fri, 14 Aug 2020 20:31:16 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0167.hostedemail.com [216.40.44.167]) by kanga.kvack.org (Postfix) with ESMTP id 527096B006E for ; Fri, 14 Aug 2020 20:31:16 -0400 (EDT) Received: from smtpin22.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 18041181AEF2A for ; Sat, 15 Aug 2020 00:31:16 +0000 (UTC) X-FDA: 77150923752.22.range96_3f086c227001 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin22.hostedemail.com (Postfix) with ESMTP id DB67718038E60 for ; Sat, 15 Aug 2020 00:31:15 +0000 (UTC) X-HE-Tag: range96_3f086c227001 X-Filterd-Recvd-Size: 3579 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf29.hostedemail.com (Postfix) with ESMTP for ; Sat, 15 Aug 2020 00:31:15 +0000 (UTC) Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 69E4622CAF; Sat, 15 Aug 2020 00:31:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597451474; bh=AvFXvOLAEDFOlsmkx/t3SRcMu/M1D+WAgX+MfEVh7iQ=; h=Date:From:To:Subject:In-Reply-To:From; b=b4wgoM9tgM8HqZJY+ZvCfd5Sk/Ylt9Lg4jV9bpqBSy939tSsLzm9aegJpsKl3aa9P 1EyesqJxFXROhKs+q8j9CEqbffz/NXfIyC+CqsHMSJCBPDMAkLi3tWtrcMEW9ZFw/4 mQlmmfyW/1VfkehFwF2rVVvqv3cFPPGRB2f5H6L4= Date: Fri, 14 Aug 2020 17:31:14 -0700 From: Andrew Morton To: akpm@linux-foundation.org, cai@lca.pw, catalin.marinas@arm.com, elver@google.com, linux-mm@kvack.org, mm-commits@vger.kernel.org, torvalds@linux-foundation.org Subject: [patch 20/39] mm/kmemleak: silence KCSAN splats in checksum Message-ID: <20200815003114.m8MWd8xqQ%akpm@linux-foundation.org> In-Reply-To: <20200814172939.55d6d80b6e21e4241f1ee1f3@linux-foundation.org> User-Agent: s-nail v14.8.16 X-Rspamd-Queue-Id: DB67718038E60 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam05 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000004, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Qian Cai Subject: mm/kmemleak: silence KCSAN splats in checksum Even if KCSAN is disabled for kmemleak, update_checksum() could still call crc32() (which is outside of kmemleak.c) to dereference object->pointer. Thus, the value of object->pointer could be accessed concurrently as noticed by KCSAN, BUG: KCSAN: data-race in crc32_le_base / do_raw_spin_lock write to 0xffffb0ea683a7d50 of 4 bytes by task 23575 on cpu 12: do_raw_spin_lock+0x114/0x200 debug_spin_lock_after at kernel/locking/spinlock_debug.c:91 (inlined by) do_raw_spin_lock at kernel/locking/spinlock_debug.c:115 _raw_spin_lock+0x40/0x50 __handle_mm_fault+0xa9e/0xd00 handle_mm_fault+0xfc/0x2f0 do_page_fault+0x263/0x6f9 page_fault+0x34/0x40 read to 0xffffb0ea683a7d50 of 4 bytes by task 839 on cpu 60: crc32_le_base+0x67/0x350 crc32_le_base+0x67/0x350: crc32_body at lib/crc32.c:106 (inlined by) crc32_le_generic at lib/crc32.c:179 (inlined by) crc32_le at lib/crc32.c:197 kmemleak_scan+0x528/0xd90 update_checksum at mm/kmemleak.c:1172 (inlined by) kmemleak_scan at mm/kmemleak.c:1497 kmemleak_scan_thread+0xcc/0xfa kthread+0x1e0/0x200 ret_from_fork+0x27/0x50 If a shattered value was returned due to a data race, it will be corrected in the next scan. Thus, let KCSAN ignore all reads in the region to silence KCSAN in case the write side is non-atomic. Link: http://lkml.kernel.org/r/20200317182754.2180-1-cai@lca.pw Signed-off-by: Qian Cai Suggested-by: Marco Elver Acked-by: Marco Elver Acked-by: Catalin Marinas Signed-off-by: Andrew Morton --- mm/kmemleak.c | 2 ++ 1 file changed, 2 insertions(+) --- a/mm/kmemleak.c~mm-kmemleak-silence-kcsan-splats-in-checksum +++ a/mm/kmemleak.c @@ -1169,8 +1169,10 @@ static bool update_checksum(struct kmeml u32 old_csum = object->checksum; kasan_disable_current(); + kcsan_disable_current(); object->checksum = crc32(0, (void *)object->pointer, object->size); kasan_enable_current(); + kcsan_enable_current(); return object->checksum != old_csum; } _