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From: Michael Stapelberg <michael+lkml@stapelberg.ch>
To: Miklos Szeredi <miklos@szeredi.hu>
Cc: fuse-devel <fuse-devel@lists.sourceforge.net>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Kyle Sanderson <kyle.leet@gmail.com>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: Still a pretty bad time on 5.4.6 with fuse_request_end.
Date: Thu, 13 Feb 2020 08:23:07 +0100	[thread overview]
Message-ID: <CANnVG6=u8drSyKhF9Gjd-Y-saN8gdOSOsmEJenyWXsQE9QYmVQ@mail.gmail.com> (raw)
In-Reply-To: <CAJfpegvBguKcNZk-p7sAtSuNH_7HfdCyYvo8Wh7X6P=hT=kPrA@mail.gmail.com>

I confirm that the patch fixes the issue I was seeing. Thanks a lot!

On Wed, Feb 12, 2020 at 8:36 PM Miklos Szeredi <miklos@szeredi.hu> wrote:
>
> On Wed, Feb 12, 2020 at 10:38 AM Michael Stapelberg
> <michael+lkml@stapelberg.ch> wrote:
> >
> > Unfortunately not: when I change the code like so:
> >
> >     bool async;
> >     uint32_t opcode_early = req->args->opcode;
> >
> >     if (test_and_set_bit(FR_FINISHED, &req->flags))
> >         goto put_request;
> >
> >     async = req->args->end;
> >
> > …gdb only reports:
> >
> > (gdb) bt
> > #0  0x000000a700000001 in ?? ()
> > #1  0xffffffff8137fc99 in fuse_copy_finish (cs=0x20000ffffffff) at
> > fs/fuse/dev.c:681
> > Backtrace stopped: previous frame inner to this frame (corrupt stack?)
> >
> > But maybe that’s a hint in and of itself?
>
> Yep, it's a stack use after return bug.   Attached patch should fix
> it, though I haven't tested it.
>
> Thanks,
> Miklos

  reply	other threads:[~2020-02-13  7:23 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-05  1:15 Still a pretty bad time on 5.4.6 with fuse_request_end Kyle Sanderson
2020-01-05  8:08 ` Greg KH
2020-01-16 11:06 ` Miklos Szeredi
2020-02-09  8:09   ` michael+lkml
2020-02-11 10:55     ` Miklos Szeredi
2020-02-12  7:58       ` Michael Stapelberg
2020-02-12  8:34         ` Miklos Szeredi
2020-02-12  9:38           ` Michael Stapelberg
2020-02-12 19:36             ` Miklos Szeredi
2020-02-13  7:23               ` Michael Stapelberg [this message]
2020-03-10 18:07               ` Vivek Goyal
2020-03-06  9:31 Bruno Thomsen
2020-03-09 19:03 ` Greg KH

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