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=-6.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 58519C55199 for ; Mon, 27 Apr 2020 14:08:57 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 183672051A for ; Mon, 27 Apr 2020 14:08:56 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="TKP0Ja9G" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 183672051A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 88F948E0005; Mon, 27 Apr 2020 10:08:56 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 83F018E0001; Mon, 27 Apr 2020 10:08:56 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 72DB88E0005; Mon, 27 Apr 2020 10:08:56 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0159.hostedemail.com [216.40.44.159]) by kanga.kvack.org (Postfix) with ESMTP id 5C70D8E0001 for ; Mon, 27 Apr 2020 10:08:56 -0400 (EDT) Received: from smtpin01.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 1F057824805A for ; Mon, 27 Apr 2020 14:08:56 +0000 (UTC) X-FDA: 76753816272.01.water98_4df70b30f122c X-HE-Tag: water98_4df70b30f122c X-Filterd-Recvd-Size: 5761 Received: from us-smtp-delivery-1.mimecast.com (us-smtp-2.mimecast.com [205.139.110.61]) by imf03.hostedemail.com (Postfix) with ESMTP for ; Mon, 27 Apr 2020 14:08:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1587996535; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc; bh=vwkVlBvgQUCTQoKNdaFgr/X8X7je3qN7klAliwiFuU8=; b=TKP0Ja9Gy07kCxTPXli2EPSI0ancuLHPfy4vW4iWHVsCj7TPknsyZstiORpsulLeG05JHt fGKZwCWmJtNgzbDTqn+JGPlyaLYZgunzhPsjrC9ero1iSEIEZmwGNE1W4NG9o8/7eUlYZb MzEwGbmDhVkC0Y/7x4nVoBKMv6+I0oQ= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-426-pO6NlNGKO12NwOUKC-6Lfg-1; Mon, 27 Apr 2020 10:08:51 -0400 X-MC-Unique: pO6NlNGKO12NwOUKC-6Lfg-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id B2425835B8D; Mon, 27 Apr 2020 14:08:49 +0000 (UTC) Received: from llong.com (ovpn-118-57.rdu2.redhat.com [10.10.118.57]) by smtp.corp.redhat.com (Postfix) with ESMTP id D13EE6062E; Mon, 27 Apr 2020 14:08:42 +0000 (UTC) From: Waiman Long To: Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Kees Cook Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Changbin Du , Matthew Wilcox , Waiman Long Subject: [PATCH v2] mm/slub: Fix incorrect interpretation of s->offset Date: Mon, 27 Apr 2020 10:08:22 -0400 Message-Id: <20200427140822.18619-1-longman@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: In a couple of places in the slub memory allocator, the code uses "s->offset" as a check to see if the free pointer is put right after the object. That check is no longer true with commit 3202fa62fb43 ("slub: relocate freelist pointer to middle of object"). As a result, echoing "1" into the validate sysfs file, e.g. of dentry, may cause a bunch of "Freepointer corrupt" error reports like the following to appear with the system in panic afterwards. [ 38.579769] ============================================================================= [ 38.580845] BUG dentry(666:pmcd.service) (Tainted: G B): Freepointer corrupt [ 38.581948] ----------------------------------------------------------------------------- To fix it, use the check "s->offset == s->inuse" in the new helper function freeptr_after_object() instead. Also add another helper function get_info_end() to return the end of info block (inuse + free pointer if not overlapping with object). Fixes: 3202fa62fb43 ("slub: relocate freelist pointer to middle of object") Signed-off-by: Waiman Long --- mm/slub.c | 37 ++++++++++++++++++++++--------------- 1 file changed, 22 insertions(+), 15 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index 0e736d66bb42..68f1b4b1c309 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -551,15 +551,29 @@ static void print_section(char *level, char *text, u8 *addr, metadata_access_disable(); } +static inline bool freeptr_after_object(struct kmem_cache *s) +{ + return s->offset == s->inuse; +} + +/* + * Return offset of the end of info block which is inuse + free pointer if + * not overlapping with object. + */ +static inline unsigned int get_info_end(struct kmem_cache *s) +{ + if (freeptr_after_object(s)) + return s->inuse + sizeof(void *); + else + return s->inuse; +} + static struct track *get_track(struct kmem_cache *s, void *object, enum track_item alloc) { struct track *p; - if (s->offset) - p = object + s->offset + sizeof(void *); - else - p = object + s->inuse; + p = object + get_info_end(s); return p + alloc; } @@ -693,10 +707,7 @@ static void print_trailer(struct kmem_cache *s, struct page *page, u8 *p) print_section(KERN_ERR, "Redzone ", p + s->object_size, s->inuse - s->object_size); - if (s->offset) - off = s->offset + sizeof(void *); - else - off = s->inuse; + off = get_info_end(s); if (s->flags & SLAB_STORE_USER) off += 2 * sizeof(struct track); @@ -790,7 +801,7 @@ static int check_bytes_and_report(struct kmem_cache *s, struct page *page, * object address * Bytes of the object to be managed. * If the freepointer may overlay the object then the free - * pointer is the first word of the object. + * pointer is at the middle of the object. * * Poisoning uses 0x6b (POISON_FREE) and the last byte is * 0xa5 (POISON_END) @@ -824,11 +835,7 @@ static int check_bytes_and_report(struct kmem_cache *s, struct page *page, static int check_pad_bytes(struct kmem_cache *s, struct page *page, u8 *p) { - unsigned long off = s->inuse; /* The end of info */ - - if (s->offset) - /* Freepointer is placed after the object. */ - off += sizeof(void *); + unsigned long off = get_info_end(s); /* The end of info */ if (s->flags & SLAB_STORE_USER) /* We also have user information there */ @@ -915,7 +922,7 @@ static int check_object(struct kmem_cache *s, struct page *page, check_pad_bytes(s, page, p); } - if (!s->offset && val == SLUB_RED_ACTIVE) + if (!freeptr_after_object(s) && val == SLUB_RED_ACTIVE) /* * Object and freepointer overlap. Cannot check * freepointer while object is allocated. -- 2.18.1