From: Masami Hiramatsu <mhiramat@kernel.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>,
linux-kernel@vger.kernel.org, Ingo Molnar <mingo@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Masami Hiramatsu <mhiramat@kernel.org>
Subject: Re: kprobes vs __ex_table[]
Date: Wed, 1 Mar 2017 01:16:51 +0900 [thread overview]
Message-ID: <20170301011651.d9961aee415783f3c7b78b19@kernel.org> (raw)
In-Reply-To: <20170224092646.GL6515@twins.programming.kicks-ass.net>
Hi Peter,
On Fri, 24 Feb 2017 10:26:46 +0100
Peter Zijlstra <peterz@infradead.org> wrote:
> One more complication with __ex_table and optimized kprobes is that we
> need to be careful not to clobber __ex_table[].fixup. It would be very
> bad if the optimized probe were to clobber the address we let the fixup
> return to -- or that needs fixups too, _after_ running
> __ex_table[].handler().
This gave me a chance to read closer current code, and I found that
I made a mistake 5 years ago on kprobe-booster. The commit 464846888d9a
("x86/kprobes: Fix a bug which can modify kernel code permanently")
introduced another bug -- which passed the address of copied instruction
instead of probing address to search_exception_tables() when preparing
kprobe-booster (skips singlestep.)
I'll send a fix patch.
Thank you,
--
Masami Hiramatsu <mhiramat@kernel.org>
next prev parent reply other threads:[~2017-02-28 16:17 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-23 18:30 Peter Zijlstra
2017-02-24 1:04 ` Masami Hiramatsu
2017-02-24 9:26 ` Peter Zijlstra
2017-02-24 16:34 ` Masami Hiramatsu
2017-02-24 17:48 ` Peter Zijlstra
2017-02-27 16:12 ` [RFC PATCH 0/2] kprobes/x86: Handle probing on ex_table cases Masami Hiramatsu
2017-02-27 16:13 ` [RFC PATCH 1/2] kprobes/x86: Use probe_kernel_read instead of memcpy Masami Hiramatsu
2017-02-27 16:14 ` [RFC PATCH 2/2] kprobes/x86: Exit single-stepping before trying fixup_exception Masami Hiramatsu
2017-03-01 23:30 ` Masami Hiramatsu
2017-02-28 16:16 ` Masami Hiramatsu [this message]
2017-02-28 16:23 ` [PATCH] [BUGFIX] kprobes/x86: Fix to check __ex_table entry by probed address Masami Hiramatsu
2017-03-01 9:13 ` [tip:perf/urgent] kprobes/x86: Fix kernel panic when certain exception-handling addresses are probed tip-bot for Masami Hiramatsu
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