From: Souptick Joarder <jrdr.linux@gmail.com>
To: Hillf Danton <hdanton@sina.com>
Cc: syzbot <syzbot+c5d5a51dcbb558ca0cb5@syzkaller.appspotmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org, Linux-MM <linux-mm@kvack.org>,
Miaohe Lin <linmiaohe@huawei.com>,
syzkaller-bugs@googlegroups.com
Subject: Re: general protection fault in unlink_file_vma
Date: Thu, 10 Sep 2020 07:43:41 +0530 [thread overview]
Message-ID: <CAFqt6zZPm=MRfYVMEZMv3KPKmxxJW=vPEWhhXbKKJ7t1tDNgPA@mail.gmail.com> (raw)
In-Reply-To: <20200909041537.19628-1-hdanton@sina.com>
Hi Hiff,
On Wed, Sep 9, 2020 at 9:45 AM Hillf Danton <hdanton@sina.com> wrote:
>
>
> Tue, 08 Sep 2020 17:19:17 -0700
> > syzbot found the following issue on:
> >
> > HEAD commit: 59126901 Merge tag 'perf-tools-fixes-for-v5.9-2020-09-03' ..
> > git tree: upstream
> > console output: https://syzkaller.appspot.com/x/log.txt?x=1166cb5d900000
> > kernel config: https://syzkaller.appspot.com/x/.config?x=3c5f6ce8d5b68299
> > dashboard link: https://syzkaller.appspot.com/bug?extid=c5d5a51dcbb558ca0cb5
> > compiler: gcc (GCC) 10.1.0-syz 20200507
> > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11901e95900000
> > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15f56195900000
> >
> > Bisection is inconclusive: the issue happens on the oldest tested release.
> >
> > bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1205faed900000
> > final oops: https://syzkaller.appspot.com/x/report.txt?x=1105faed900000
> > console output: https://syzkaller.appspot.com/x/log.txt?x=1605faed900000
> >
> > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > Reported-by: syzbot+c5d5a51dcbb558ca0cb5@syzkaller.appspotmail.com
> >
> > general protection fault, probably for non-canonical address 0xe00eeaee0000003b: 0000 [#1] PREEMPT SMP KASAN
> > KASAN: maybe wild-memory-access in range [0x00777770000001d8-0x00777770000001df]
> > CPU: 1 PID: 10488 Comm: syz-executor721 Not tainted 5.9.0-rc3-syzkaller #0
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> > RIP: 0010:unlink_file_vma+0x57/0xb0 mm/mmap.c:164
> > Code: 4c 8b a5 a0 00 00 00 4d 85 e4 74 4e e8 92 d7 cd ff 49 8d bc 24 d8 01 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 75 3d 4d 8b b4 24 d8 01 00 00 4d 8d 6e 78 4c 89 ef e8
> > RSP: 0018:ffffc9000ac0f9b0 EFLAGS: 00010202
> > RAX: dffffc0000000000 RBX: ffff88800010ceb0 RCX: ffffffff81592421
> > RDX: 000eeeee0000003b RSI: ffffffff81a6736e RDI: 00777770000001d8
> > RBP: ffff88800010ceb0 R08: 0000000000000001 R09: ffff88801291a50f
> > R10: ffffed10025234a1 R11: 0000000000000001 R12: 0077777000000000
> > R13: 00007f1eea0da000 R14: 00007f1eea0d9000 R15: 0000000000000000
> > FS: 0000000000000000(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000
> > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > CR2: 00007f1eea11a9d0 CR3: 000000000007e000 CR4: 00000000001506e0
> > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> > Call Trace:
> > free_pgtables+0x1b3/0x2f0 mm/memory.c:415
> > exit_mmap+0x2c0/0x530 mm/mmap.c:3184
> > __mmput+0x122/0x470 kernel/fork.c:1076
> > mmput+0x53/0x60 kernel/fork.c:1097
> > exit_mm kernel/exit.c:483 [inline]
> > do_exit+0xa8b/0x29f0 kernel/exit.c:793
> > do_group_exit+0x125/0x310 kernel/exit.c:903
> > get_signal+0x428/0x1f00 kernel/signal.c:2757
> > arch_do_signal+0x82/0x2520 arch/x86/kernel/signal.c:811
> > exit_to_user_mode_loop kernel/entry/common.c:136 [inline]
> > exit_to_user_mode_prepare+0x1ae/0x200 kernel/entry/common.c:167
> > syscall_exit_to_user_mode+0x7e/0x2e0 kernel/entry/common.c:242
> > entry_SYSCALL_64_after_hwframe+0x44/0xa9
>
> Looks like d70cec898324 ("mm: mmap: merge vma after call_mmap() if possible")
> added an extra fput.
Can you please help me to understand how do you figure out this commit ?
>
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -1781,7 +1781,6 @@ unsigned long mmap_region(struct file *f
> merge = vma_merge(mm, prev, vma->vm_start, vma->vm_end, vma->vm_flags,
> NULL, vma->vm_file, vma->vm_pgoff, NULL, NULL_VM_UFFD_CTX);
> if (merge) {
> - fput(file);
> vm_area_free(vma);
> vma = merge;
> /* Update vm_flags and possible addr to pick up the change. We don't
>
>
next prev parent reply other threads:[~2020-09-10 2:13 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-09 0:19 syzbot
2020-09-09 4:15 ` Hillf Danton
2020-09-10 2:13 ` Souptick Joarder [this message]
2020-09-10 4:17 ` Hillf Danton
2020-09-10 6:26 linmiaohe
2020-09-13 9:17 linmiaohe
2020-09-13 11:16 ` Hillf Danton
2020-09-14 1:51 linmiaohe
2020-09-14 6:42 linmiaohe
2020-09-15 11:13 linmiaohe
2020-09-16 1:48 linmiaohe
2020-09-16 4:24 ` syzbot
2020-09-16 6:50 linmiaohe
2020-09-16 8:39 ` syzbot
2020-09-16 9:05 linmiaohe
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CAFqt6zZPm=MRfYVMEZMv3KPKmxxJW=vPEWhhXbKKJ7t1tDNgPA@mail.gmail.com' \
--to=jrdr.linux@gmail.com \
--cc=akpm@linux-foundation.org \
--cc=hdanton@sina.com \
--cc=linmiaohe@huawei.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=syzbot+c5d5a51dcbb558ca0cb5@syzkaller.appspotmail.com \
--cc=syzkaller-bugs@googlegroups.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox