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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D8B80C433EF for ; Mon, 9 May 2022 15:48:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238621AbiEIPwj (ORCPT ); Mon, 9 May 2022 11:52:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56156 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238529AbiEIPwg (ORCPT ); Mon, 9 May 2022 11:52:36 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 9D8672D76E7 for ; Mon, 9 May 2022 08:48:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1652111320; h=from:from: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=t41mLb2CHoozgZBbJV2mqxblkUXL3qgQ9BaS0ec36pA=; b=GqrnichxuzzoFhFp9vsdwUNagoGoumxv+LtFYRF48pUli2oyAS9AIksk4oLoWukG6gw4NV 0msD7nyTElo6fBl2Uz9kvXkvE4S3d7f70co4sOrQxd5+dqyXk6OJ+gtwWQN8cEREe4EUNC 7EncwWMflYyS0w6s4poxLWmvw2bY04k= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-135-7hH4sju1OWekDDaQwxs_FQ-1; Mon, 09 May 2022 11:48:29 -0400 X-MC-Unique: 7hH4sju1OWekDDaQwxs_FQ-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.rdu2.redhat.com [10.11.54.2]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 58FB5801E80; Mon, 9 May 2022 15:48:29 +0000 (UTC) Received: from [10.18.17.215] (dhcp-17-215.bos.redhat.com [10.18.17.215]) by smtp.corp.redhat.com (Postfix) with ESMTP id 204714010E40; Mon, 9 May 2022 15:48:29 +0000 (UTC) Message-ID: Date: Mon, 9 May 2022 11:48:28 -0400 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.8.0 Subject: Re: [PATCH] mm/page_owner: use strscpy() instead of strlcpy() Content-Language: en-US To: Eric Dumazet , Andrew Morton Cc: linux-kernel , linux-mm , Eric Dumazet , syzbot References: <20220509145949.265184-1-eric.dumazet@gmail.com> From: Waiman Long In-Reply-To: <20220509145949.265184-1-eric.dumazet@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.11.54.2 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/9/22 10:59, Eric Dumazet wrote: > From: Eric Dumazet > > current->comm[] is not a string (no guarantee for > a zero byte in it). > > strlcpy(s1, s2, l) is calling strlen(s2), potentially > causing out-of-bound access, as reported by syzbot: > > detected buffer overflow in __fortify_strlen > ------------[ cut here ]------------ > kernel BUG at lib/string_helpers.c:980! > invalid opcode: 0000 [#1] PREEMPT SMP KASAN > CPU: 0 PID: 4087 Comm: dhcpcd-run-hooks Not tainted 5.18.0-rc3-syzkaller-01537-g20b87e7c29df #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > RIP: 0010:fortify_panic+0x18/0x1a lib/string_helpers.c:980 > Code: 8c e8 c5 ba e1 fa e9 23 0f bf fa e8 0b 5d 8c f8 eb db 55 48 89 fd e8 e0 49 40 f8 48 89 ee 48 c7 c7 80 f5 26 8a e8 99 09 f1 ff <0f> 0b e8 ca 49 40 f8 48 8b 54 24 18 4c 89 f1 48 c7 c7 00 00 27 8a > RSP: 0018:ffffc900000074a8 EFLAGS: 00010286 > > RAX: 000000000000002c RBX: ffff88801226b728 RCX: 0000000000000000 > RDX: ffff8880198e0000 RSI: ffffffff81600458 RDI: fffff52000000e87 > RBP: ffffffff89da2aa0 R08: 000000000000002c R09: 0000000000000000 > R10: ffffffff815fae2e R11: 0000000000000000 R12: ffff88801226b700 > R13: ffff8880198e0830 R14: 0000000000000000 R15: 0000000000000000 > FS: 0000000000000000(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00007f5876ad6ff8 CR3: 000000001a48c000 CR4: 00000000003506f0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600 > Call Trace: > > __fortify_strlen include/linux/fortify-string.h:128 [inline] > strlcpy include/linux/fortify-string.h:143 [inline] > __set_page_owner_handle+0x2b1/0x3e0 mm/page_owner.c:171 > __set_page_owner+0x3e/0x50 mm/page_owner.c:190 > prep_new_page mm/page_alloc.c:2441 [inline] > get_page_from_freelist+0xba2/0x3e00 mm/page_alloc.c:4182 > __alloc_pages+0x1b2/0x500 mm/page_alloc.c:5408 > alloc_pages+0x1aa/0x310 mm/mempolicy.c:2272 > alloc_slab_page mm/slub.c:1799 [inline] > allocate_slab+0x26c/0x3c0 mm/slub.c:1944 > new_slab mm/slub.c:2004 [inline] > ___slab_alloc+0x8df/0xf20 mm/slub.c:3005 > __slab_alloc.constprop.0+0x4d/0xa0 mm/slub.c:3092 > slab_alloc_node mm/slub.c:3183 [inline] > slab_alloc mm/slub.c:3225 [inline] > __kmem_cache_alloc_lru mm/slub.c:3232 [inline] > kmem_cache_alloc+0x360/0x3b0 mm/slub.c:3242 > dst_alloc+0x146/0x1f0 net/core/dst.c:92 > > Fixes: 865ed6a32786 ("mm/page_owner: record task command name") > Signed-off-by: Eric Dumazet > Reported-by: syzbot > Cc: Waiman Long > --- > mm/page_owner.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/page_owner.c b/mm/page_owner.c > index fb3a05fdebdbf1c3646ba1584cbf06facf0e7a9a..19bc559e49040e60c03a5f4268c89618fa0f1b1c 100644 > --- a/mm/page_owner.c > +++ b/mm/page_owner.c > @@ -168,7 +168,7 @@ static inline void __set_page_owner_handle(struct page_ext *page_ext, > page_owner->pid = current->pid; > page_owner->tgid = current->tgid; > page_owner->ts_nsec = local_clock(); > - strlcpy(page_owner->comm, current->comm, > + strscpy(page_owner->comm, current->comm, > sizeof(page_owner->comm)); > __set_bit(PAGE_EXT_OWNER, &page_ext->flags); > __set_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags); Yes, I think it is more correct to use strscpy(). Acked-by: Waiman Long Thanks, Longman