From: Srikar Dronamraju <srikar@linux•vnet.ibm.com>
To: Ravi Bangoria <ravi.bangoria@linux•ibm.com>
Cc: linux-mips@linux-mips•org, linux@armlinux•org.uk,
peterz@infradead•org, jolsa@redhat•com, ralf@linux-mips•org,
liu.song.a23@gmail•com, oleg@redhat•com, rostedt@goodmis•org,
linux-kernel@vger•kernel.org, alexander.shishkin@linux•intel.com,
paul.burton@mips•com, mingo@redhat•com, mhiramat@kernel•org,
ananth@linux•vnet.ibm.com, namhyung@kernel•org,
naveen.n.rao@linux•vnet.ibm.com, alexis.berlemont@gmail•com,
acme@kernel•org, linux-arm-kernel@lists•infradead.org
Subject: Re: [PATCH v2] Uprobes: Fix kernel oops with delayed_uprobe_remove()
Date: Wed, 5 Dec 2018 15:31:41 +0530 [thread overview]
Message-ID: <20181205100141.GA8473@linux.vnet.ibm.com> (raw)
In-Reply-To: <20181205033423.26242-1-ravi.bangoria@linux.ibm.com>
* Ravi Bangoria <ravi.bangoria@linux•ibm.com> [2018-12-05 09:04:23]:
> There could be a race between task exit and probe unregister:
>
> exit_mm()
> mmput()
> __mmput() uprobe_unregister()
> uprobe_clear_state() put_uprobe()
> delayed_uprobe_remove() delayed_uprobe_remove()
>
> put_uprobe() is calling delayed_uprobe_remove() without taking
> delayed_uprobe_lock and thus the race sometimes results in a
> kernel crash. Fix this by taking delayed_uprobe_lock before
> calling delayed_uprobe_remove() from put_uprobe().
>
> Detailed crash log can be found at:
> https://lkml.org/lkml/2018/11/1/1244
>
> Reported-by: syzbot+cb1fb754b771caca0a88@syzkaller•appspotmail.com
> Fixes: 1cc33161a83d ("uprobes: Support SDT markers having reference count (semaphore)")
> Signed-off-by: Ravi Bangoria <ravi.bangoria@linux•ibm.com>
Looks good to me.
Reviewed-by: Srikar Dronamraju <srikar@linux•vnet.ibm.com>
> ---
> kernel/events/uprobes.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
> index 322e97bbb437..abbd8da9ac21 100644
> --- a/kernel/events/uprobes.c
> +++ b/kernel/events/uprobes.c
> @@ -572,7 +572,9 @@ static void put_uprobe(struct uprobe *uprobe)
> * gets called, we don't get a chance to remove uprobe from
> * delayed_uprobe_list from remove_breakpoint(). Do it here.
> */
> + mutex_lock(&delayed_uprobe_lock);
> delayed_uprobe_remove(uprobe, NULL);
> + mutex_unlock(&delayed_uprobe_lock);
> kfree(uprobe);
> }
> }
> --
> 2.19.2
>
--
Thanks and Regards
Srikar Dronamraju
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next prev parent reply other threads:[~2018-12-05 10:02 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-14 8:19 [PATCH] Uprobes: Fix kernel oops with delayed_uprobe_remove() Ravi Bangoria
2018-11-14 16:06 ` Oleg Nesterov
2018-11-15 4:06 ` Ravi Bangoria
2018-11-15 12:43 ` Oleg Nesterov
2018-12-03 6:22 ` Ravi Bangoria
2018-12-04 5:58 ` Steven Rostedt
2018-12-05 3:34 ` [PATCH v2] " Ravi Bangoria
2018-12-05 10:01 ` Srikar Dronamraju [this message]
2018-12-05 14:39 ` Oleg Nesterov
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