From: Oleg Nesterov <oleg@redhat.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Borislav Petkov <bp@alien8.de>,
Mark Mossberg <mark.mossberg@gmail.com>,
mingo@redhat.com, x86@kernel.org, linux-kernel@vger.kernel.org,
hpa@zytor.com, jannh@google.com, kyin@redhat.com
Subject: Re: [PATCH v2] x86/dumpstack: Fix misleading instruction pointer error message
Date: Tue, 17 Nov 2020 18:31:53 +0100 [thread overview]
Message-ID: <20201117173152.GA26898@redhat.com> (raw)
In-Reply-To: <87blfxx8ps.fsf@nanos.tec.linutronix.de>
On 11/16, Thomas Gleixner wrote:
>
> Subject: x86/dumpstack: Don't try to access user space code of other tasks
> From: Thomas Gleixner <tglx@linutronix.de>
> Date: Mon, 16 Nov 2020 22:26:52 +0100
>
> sysrq-t ends up invoking show_opcodes() for each task which tries to access
> the user space code of other processes which is obviously bogus.
>
> It either manages to dump where the foreign tasks regs->ip points to in
> currents mapping or triggers a pagefault and prints "Code: Bad RIP
> value.". Both is just wrong.
>
> Add a safeguard in copy_code() and check whether the @regs pointer matches
> currents pt_regs. If not, do not even try to access it.
>
> While at it, add commentry why using copy_from_user_nmi() is safe in
> copy_code() even if the function name suggests otherwise.
>
> Reported-by: Mark Mossberg <mark.mossberg@gmail.com>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Oleg Nesterov <oleg@redhat.com>
prev parent reply other threads:[~2020-11-17 17:32 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-02 4:29 [PATCH v2] x86/dumpstack: Fix misleading instruction pointer error message Mark Mossberg
2020-10-02 10:26 ` [tip: x86/core] " tip-bot2 for Mark Mossberg
2020-11-03 12:50 ` [PATCH v2] " Oleg Nesterov
2020-11-03 17:15 ` Borislav Petkov
2020-11-03 17:47 ` Oleg Nesterov
2020-11-03 17:52 ` Borislav Petkov
2020-11-03 18:11 ` Oleg Nesterov
2020-11-03 18:20 ` Borislav Petkov
2020-11-16 22:01 ` Thomas Gleixner
2020-11-16 23:04 ` Andy Lutomirski
2020-11-16 23:37 ` Thomas Gleixner
2020-11-17 3:29 ` Andy Lutomirski
2020-11-17 9:54 ` Borislav Petkov
2020-11-17 17:31 ` Oleg Nesterov [this message]
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