From: Steven Rostedt <rostedt@goodmis.org>
To: Beau Belgrave <beaub@linux.microsoft.com>
Cc: mhiramat@kernel.org, mathieu.desnoyers@efficios.com,
dcook@linux.microsoft.com, alanau@linux.microsoft.com,
linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org
Subject: Re: [PATCH 2/3] tracing/user_events: Ensure bit is cleared on unregister
Date: Tue, 25 Apr 2023 13:56:15 -0400 [thread overview]
Message-ID: <20230425135615.5801d0cf@gandalf.local.home> (raw)
In-Reply-To: <20230425170654.GA74@W11-BEAU-MD.localdomain>
On Tue, 25 Apr 2023 10:06:54 -0700
Beau Belgrave <beaub@linux.microsoft.com> wrote:
> That's a good point, user_event_mm_fault() is a wrapper around
> fixup_user_fault(). We retry if it works, so I guess if the user could
> somehow cause a fail on the write and succeed to page in repeatedly, it
> could keep the loop going for that time period. I cannot think of a way
> to achieve this forever, but that doesn't mean it couldn't happen.
>
> I can certainly add an upper bound of retries (maybe 3 or so?) if you
> think it would be possible for this to occur. I think we need retries of
> some amount to handle spurious faults.
Even 10 is fine. With a comment saying, "This really shouldn't loop more
than a couple of times, but we want to make sure some mischievous user
doesn't take advantage of this looping".
-- Steve
next prev parent reply other threads:[~2023-04-25 17:56 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-11 21:17 [PATCH 0/3] tracing/user_events: Fixes and improvements for 6.4 Beau Belgrave
2023-04-11 21:17 ` [PATCH 1/3] tracing/user_events: Ensure write index cannot be negative Beau Belgrave
2023-04-25 14:43 ` Masami Hiramatsu
2023-04-11 21:17 ` [PATCH 2/3] tracing/user_events: Ensure bit is cleared on unregister Beau Belgrave
2023-04-25 1:39 ` Steven Rostedt
2023-04-25 17:06 ` Beau Belgrave
2023-04-25 17:56 ` Steven Rostedt [this message]
2023-04-11 21:17 ` [PATCH 3/3] tracing/user_events: Prevent same address and bit per process Beau Belgrave
2023-04-25 1:41 ` Steven Rostedt
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