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smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 29CD78E000D; Mon, 6 Apr 2020 21:06:05 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 227D18E0001; Mon, 6 Apr 2020 21:06:05 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0C5F68E000D; Mon, 6 Apr 2020 21:06:05 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0177.hostedemail.com [216.40.44.177]) by kanga.kvack.org (Postfix) with ESMTP id EA4068E0001 for ; Mon, 6 Apr 2020 21:06:04 -0400 (EDT) Received: from smtpin04.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id B524F180AD804 for ; Tue, 7 Apr 2020 01:06:04 +0000 (UTC) X-FDA: 76679267448.04.swing29_5220192484a43 X-HE-Tag: swing29_5220192484a43 X-Filterd-Recvd-Size: 9552 Received: from mail-io1-f70.google.com (mail-io1-f70.google.com [209.85.166.70]) by imf49.hostedemail.com (Postfix) with ESMTP for ; Tue, 7 Apr 2020 01:06:04 +0000 (UTC) Received: by mail-io1-f70.google.com with SMTP id c10so1691792ioc.2 for ; Mon, 06 Apr 2020 18:06:04 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:date:in-reply-to:message-id:subject :from:to:cc; bh=e0jEEa+pjjlUz/FmgtgfrMc7L6f9YFcKjGa20T02Fkk=; b=FM9xlw5DUbH7D5+lZNxVcK2Bjx0aQm/86XiYDLYEQ/P0fUiV18QpBLNvC3gIXN/dMI hdsUdM+5OJvLBYT8y5fXNuCNUE7mR84I/jts2x+Qpnke0QJFJ0omrdmuVaq7GWXf3wCO MRuYncy7h+k2/DFNH/gP6cQR0Q4/gV1UCFVkRggNibRGSvZ4xaNuQsr0DMlxdwOTWK2j 2fDSk5HzAOYhFZtE6Bu/6CO8dGKchvzxpYluK7plnmdZlImv+oc5F6EDOuKkJA4v7roR OGxg//p1FvbA0BlnyBCNdOeSOWWkEPU0XdHhQqSNuQRsTFBvxWhrF5aZsr6x/PbG38n4 v9nw== X-Gm-Message-State: AGi0PuZALjmT/f/y2ntTVl8wxR9gP+USPTu8vvVHNqYPBnDNTWIpW/9l GnXiNr/esl9R6OjMo9fUiZ3JByO9dVwgLitk54xJ1ycJeL3p X-Google-Smtp-Source: APiQypJCzmFeaF1N49v+EvGzOgO9RTUeIQneWmNPHzGtgQsWYivAe5gsFfhTl+GcaUOXqXj7JoabDrYL3tUuFgsPjpQ0AwZoddGZ MIME-Version: 1.0 X-Received: by 2002:a5d:8742:: with SMTP id k2mr15906792iol.120.1586221563224; Mon, 06 Apr 2020 18:06:03 -0700 (PDT) Date: Mon, 06 Apr 2020 18:06:03 -0700 In-Reply-To: <3ff20c8a-5a26-5e38-42f7-ec751735d47c@infradead.org> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <000000000000cfac8f05a2a8fc83@google.com> Subject: Re: Re: BUG: unable to handle kernel paging request in kernel_get_mempolicy From: syzbot To: Randy Dunlap Cc: akpm@linux-foundation.org, bgeffon@google.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, peterx@redhat.com, rdunlap@infradead.org, syzkaller-bugs@googlegroups.com, torvalds@linux-foundation.org Content-Type: text/plain; charset="UTF-8" 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: > On 4/6/20 5:47 PM, Peter Xu wrote: >> On Mon, Apr 06, 2020 at 11:16:13AM -0700, syzbot wrote: >>> Hello, >>> >>> syzbot found the following crash on: >>> >>> HEAD commit: bef7b2a7 Merge tag 'devicetree-for-5.7' of git://git.kerne.. >>> git tree: upstream >>> console output: https://syzkaller.appspot.com/x/log.txt?x=13966e8fe00000 >>> kernel config: https://syzkaller.appspot.com/x/.config?x=91b674b8f0368e69 >>> dashboard link: https://syzkaller.appspot.com/bug?extid=693dc11fcb53120b5559 >>> compiler: gcc (GCC) 9.0.0 20181231 (experimental) >>> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1738b02be00000 >>> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17d2c76de00000 >>> >>> The bug was bisected to: >>> >>> commit 4426e945df588f2878affddf88a51259200f7e29 >>> Author: Peter Xu >>> Date: Thu Apr 2 04:08:49 2020 +0000 >>> >>> mm/gup: allow VM_FAULT_RETRY for multiple times >>> >>> bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=14ac4a5de00000 >>> final crash: https://syzkaller.appspot.com/x/report.txt?x=16ac4a5de00000 >>> console output: https://syzkaller.appspot.com/x/log.txt?x=12ac4a5de00000 >>> >>> IMPORTANT: if you fix the bug, please add the following tag to the commit: >>> Reported-by: syzbot+693dc11fcb53120b5559@syzkaller.appspotmail.com >>> Fixes: 4426e945df58 ("mm/gup: allow VM_FAULT_RETRY for multiple times") >>> >>> BUG: unable to handle page fault for address: ffffffff00000000 >>> #PF: supervisor read access in kernel mode >>> #PF: error_code(0x0000) - not-present page >>> PGD 987c067 P4D 987c067 PUD 0 >>> Oops: 0000 [#1] PREEMPT SMP KASAN >>> CPU: 1 PID: 7181 Comm: syz-executor616 Not tainted 5.6.0-syzkaller #0 >>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 >>> RIP: 0010:page_to_nid include/linux/mm.h:1245 [inline] >>> RIP: 0010:lookup_node mm/mempolicy.c:906 [inline] >>> RIP: 0010:do_get_mempolicy mm/mempolicy.c:970 [inline] >>> RIP: 0010:kernel_get_mempolicy+0x60e/0xfb0 mm/mempolicy.c:1615 >>> Code: 88 00 07 00 00 e8 b2 35 c5 ff 4c 8b 7c 24 78 48 b8 00 00 00 00 00 fc ff df 4c 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 fb 08 00 00 <49> 8b 1f 48 c7 c7 ff ff ff ff 48 89 de e8 10 37 c5 ff 48 83 fb ff >>> RSP: 0018:ffffc900018d7de8 EFLAGS: 00010246 >>> RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff81adaaf1 >>> RDX: 1fffffffe0000000 RSI: ffffffff81adaafe RDI: 0000000000000005 >>> RBP: 0000000000000000 R08: ffff88808de924c0 R09: ffffed1011bd2499 >>> R10: ffff88808de924c7 R11: ffffed1011bd2498 R12: 0000000000000000 >>> R13: 1ffff9200031afc4 R14: ffffffff89a6df60 R15: ffffffff00000000 >>> FS: 00007f848cd4a700(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000 >>> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >>> CR2: ffffffff00000000 CR3: 00000000a7a8d000 CR4: 00000000001406e0 >>> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 >>> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 >>> Call Trace: >>> __do_sys_get_mempolicy mm/mempolicy.c:1633 [inline] >>> __se_sys_get_mempolicy mm/mempolicy.c:1629 [inline] >>> __x64_sys_get_mempolicy+0xba/0x150 mm/mempolicy.c:1629 >>> do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295 >>> entry_SYSCALL_64_after_hwframe+0x49/0xb3 >>> RIP: 0033:0x446719 >>> Code: e8 5c b3 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 0b 08 fc ff c3 66 2e 0f 1f 84 00 00 00 00 >>> RSP: 002b:00007f848cd49db8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ef >>> RAX: ffffffffffffffda RBX: 00000000006dbc28 RCX: 0000000000446719 >>> RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 >>> RBP: 00000000006dbc20 R08: 0000000000000003 R09: 0000000000000000 >>> R10: 000000002073b000 R11: 0000000000000246 R12: 00000000006dbc2c >>> R13: 00007ffcfe6ba66f R14: 00007f848cd4a9c0 R15: 20c49ba5e353f7cf >>> Modules linked in: >>> CR2: ffffffff00000000 >>> ---[ end trace 0becf554e06291c3 ]--- >>> RIP: 0010:page_to_nid include/linux/mm.h:1245 [inline] >>> RIP: 0010:lookup_node mm/mempolicy.c:906 [inline] >>> RIP: 0010:do_get_mempolicy mm/mempolicy.c:970 [inline] >>> RIP: 0010:kernel_get_mempolicy+0x60e/0xfb0 mm/mempolicy.c:1615 >>> Code: 88 00 07 00 00 e8 b2 35 c5 ff 4c 8b 7c 24 78 48 b8 00 00 00 00 00 fc ff df 4c 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 fb 08 00 00 <49> 8b 1f 48 c7 c7 ff ff ff ff 48 89 de e8 10 37 c5 ff 48 83 fb ff >>> RSP: 0018:ffffc900018d7de8 EFLAGS: 00010246 >>> RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff81adaaf1 >>> RDX: 1fffffffe0000000 RSI: ffffffff81adaafe RDI: 0000000000000005 >>> RBP: 0000000000000000 R08: ffff88808de924c0 R09: ffffed1011bd2499 >>> R10: ffff88808de924c7 R11: ffffed1011bd2498 R12: 0000000000000000 >>> R13: 1ffff9200031afc4 R14: ffffffff89a6df60 R15: ffffffff00000000 >>> FS: 00007f848cd4a700(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000 >>> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >>> CR2: ffffffff00000000 CR3: 00000000a7a8d000 CR4: 00000000001406e0 >>> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 >>> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 >> >> Hi, Andrew & all, >> >> I can reproduce this locally right after I run the test program, and >> below patch fixed it for me - the test program can run with quite a >> few minutes without crashing again. >> >> Is there a way I can feed this to the syzbot to re-verify this? > > Hi Peter, > > Send the patch. At the top of the email, put something like > #syz test want 2 args (repo, branch), got 3 > > It's documented here: > https://github.com/google/syzkaller/blob/master/docs/syzbot.md > > >> Thanks, >> >> 8<--------------------------------------------------------------- >> From 23800bff6fa346a4e9b3806dc0cfeb74498df757 Mon Sep 17 00:00:00 2001 >> From: Peter Xu >> Date: Mon, 6 Apr 2020 20:40:13 -0400 >> Subject: [PATCH] mm/mempolicy: Allow lookup_node() to handle fatal signal >> >> lookup_node() uses gup to pin the page and get node information. It >> checks against ret>=0 assuming the page will be filled in. However >> it's also possible that gup will return zero, for example, when the >> thread is quickly killed with a fatal signal. Teach lookup_node() to >> gracefully return an error -EFAULT if it happens. >> >> Reported-by: syzbot+693dc11fcb53120b5559@syzkaller.appspotmail.com >> Fixes: 4426e945df58 ("mm/gup: allow VM_FAULT_RETRY for multiple times") >> Signed-off-by: Peter Xu >> --- >> mm/mempolicy.c | 5 ++++- >> 1 file changed, 4 insertions(+), 1 deletion(-) >> >> diff --git a/mm/mempolicy.c b/mm/mempolicy.c >> index 5fb427aed612..1398578db025 100644 >> --- a/mm/mempolicy.c >> +++ b/mm/mempolicy.c >> @@ -902,7 +902,10 @@ static int lookup_node(struct mm_struct *mm, unsigned long addr) >> >> int locked = 1; >> err = get_user_pages_locked(addr & PAGE_MASK, 1, 0, &p, &locked); >> - if (err >= 0) { >> + if (err == 0) { >> + /* E.g. GUP interupted by fatal signal */ >> + err = -EFAULT; >> + } else if (err > 0) { >> err = page_to_nid(p); >> put_page(p); >> } >> > > > > -- > ~Randy > Reported-by: Randy Dunlap