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From: Marc Zyngier <maz@kernel.org>
To: Fredrik Strupe <fredrik@strupe.net>
Cc: Russell King <linux@armlinux.org.uk>,
	Rabin Vincent <rabin@rab.in>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] arm: uprobes: Don't hook on thumb instructions
Date: Wed, 31 Mar 2021 14:42:52 +0100	[thread overview]
Message-ID: <875z17qw0z.wl-maz@kernel.org> (raw)
In-Reply-To: <20200518125948.25315-1-fredrik@strupe.net>

Hi Fredrik,

On  Mon, 18 May 2020, Fredrik Strupe wrote:
> Since uprobes is not supported for thumb, check that the thumb bit is
> not set when matching the uprobes instruction hooks.
>
> The Arm UDF instructions used for uprobes triggering
> (UPROBE_SWBP_ARM_INSN and UPROBE_SS_ARM_INSN) coincidentally share the
> same encoding as a pair of unallocated 32-bit thumb instructions (not
> UDF) when the condition code is 0b1111 (0xf). This in effect makes it
> possible to trigger the uprobes functionality from thumb, and at that
> using two unallocated instructions which are not permanently
> undefined.
>
> Signed-off-by: Fredrik Strupe <fredrik@strupe.net
> Fixes: c7edc9e326d5 ("ARM: add uprobes support")

It looks like we dropped the ball on this patch. Could you please add
it to Russell's patch system, together with a Cc: stable?

Otherwise, just say the word and I'll do it for you.

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.

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WARNING: multiple messages have this Message-ID (diff)
From: Marc Zyngier <maz@kernel.org>
To: Fredrik Strupe <fredrik@strupe.net>
Cc: Russell King <linux@armlinux.org.uk>,
	Rabin Vincent <rabin@rab.in>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] arm: uprobes: Don't hook on thumb instructions
Date: Wed, 31 Mar 2021 14:42:52 +0100	[thread overview]
Message-ID: <875z17qw0z.wl-maz@kernel.org> (raw)
In-Reply-To: <20200518125948.25315-1-fredrik@strupe.net>

Hi Fredrik,

On  Mon, 18 May 2020, Fredrik Strupe wrote:
> Since uprobes is not supported for thumb, check that the thumb bit is
> not set when matching the uprobes instruction hooks.
>
> The Arm UDF instructions used for uprobes triggering
> (UPROBE_SWBP_ARM_INSN and UPROBE_SS_ARM_INSN) coincidentally share the
> same encoding as a pair of unallocated 32-bit thumb instructions (not
> UDF) when the condition code is 0b1111 (0xf). This in effect makes it
> possible to trigger the uprobes functionality from thumb, and at that
> using two unallocated instructions which are not permanently
> undefined.
>
> Signed-off-by: Fredrik Strupe <fredrik@strupe.net
> Fixes: c7edc9e326d5 ("ARM: add uprobes support")

It looks like we dropped the ball on this patch. Could you please add
it to Russell's patch system, together with a Cc: stable?

Otherwise, just say the word and I'll do it for you.

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.

  reply	other threads:[~2021-03-31 13:44 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-18 12:59 [PATCH] arm: uprobes: Don't hook on thumb instructions Fredrik Strupe
2020-05-18 12:59 ` Fredrik Strupe
2021-03-31 13:42 ` Marc Zyngier [this message]
2021-03-31 13:42   ` Marc Zyngier

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