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From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Michael Ellerman <mpe@ellerman.id.au>,
	Segher Boessenkool <segher@kernel.crashing.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	pmenzel@molgen.mpg.de, linuxppc-dev@lists.ozlabs.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] powerpc/legacy_serial: Fix UBSAN: array-index-out-of-bounds
Date: Tue, 11 May 2021 06:54:14 +0200	[thread overview]
Message-ID: <c3d6c5c5-0eb8-bad5-91f9-fea01eaeef37@csgroup.eu> (raw)
In-Reply-To: <87sg2uxe7h.fsf@mpe.ellerman.id.au>



Le 11/05/2021 à 03:16, Michael Ellerman a écrit :
> Segher Boessenkool <segher@kernel.crashing.org> writes:
> 
>> On Sat, May 08, 2021 at 06:36:21AM +0000, Christophe Leroy wrote:
>>> UBSAN complains when a pointer is calculated with invalid
>>> 'legacy_serial_console' index, allthough the index is verified
>>> before dereferencing the pointer.
>>
>> Addressing like this is UB already.
>>
>> You could just move this:
>>
>>> -	if (legacy_serial_console < 0)
>>> -		return 0;
>>
>> to before
>>
>>> -	struct legacy_serial_info *info = &legacy_serial_infos[legacy_serial_console];
>>> -	struct plat_serial8250_port *port = &legacy_serial_ports[legacy_serial_console];
>>
>> and no other change is necessary.
> 
> Yeah I sent a v2 doing that, thanks.
> 

I wanted something looking similar to setup_legacy_serial_console(), but of course this also works.

Christophe

WARNING: multiple messages have this Message-ID (diff)
From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Michael Ellerman <mpe@ellerman.id.au>,
	Segher Boessenkool <segher@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>,
	linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
	pmenzel@molgen.mpg.de
Subject: Re: [PATCH] powerpc/legacy_serial: Fix UBSAN: array-index-out-of-bounds
Date: Tue, 11 May 2021 06:54:14 +0200	[thread overview]
Message-ID: <c3d6c5c5-0eb8-bad5-91f9-fea01eaeef37@csgroup.eu> (raw)
In-Reply-To: <87sg2uxe7h.fsf@mpe.ellerman.id.au>



Le 11/05/2021 à 03:16, Michael Ellerman a écrit :
> Segher Boessenkool <segher@kernel.crashing.org> writes:
> 
>> On Sat, May 08, 2021 at 06:36:21AM +0000, Christophe Leroy wrote:
>>> UBSAN complains when a pointer is calculated with invalid
>>> 'legacy_serial_console' index, allthough the index is verified
>>> before dereferencing the pointer.
>>
>> Addressing like this is UB already.
>>
>> You could just move this:
>>
>>> -	if (legacy_serial_console < 0)
>>> -		return 0;
>>
>> to before
>>
>>> -	struct legacy_serial_info *info = &legacy_serial_infos[legacy_serial_console];
>>> -	struct plat_serial8250_port *port = &legacy_serial_ports[legacy_serial_console];
>>
>> and no other change is necessary.
> 
> Yeah I sent a v2 doing that, thanks.
> 

I wanted something looking similar to setup_legacy_serial_console(), but of course this also works.

Christophe

  reply	other threads:[~2021-05-11  4:54 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-08  6:36 [PATCH] powerpc/legacy_serial: Fix UBSAN: array-index-out-of-bounds Christophe Leroy
2021-05-08  6:36 ` Christophe Leroy
2021-05-10 21:14 ` Segher Boessenkool
2021-05-10 21:14   ` Segher Boessenkool
2021-05-11  1:16   ` Michael Ellerman
2021-05-11  1:16     ` Michael Ellerman
2021-05-11  4:54     ` Christophe Leroy [this message]
2021-05-11  4:54       ` Christophe Leroy
2021-05-15 22:43 ` Michael Ellerman
2021-05-15 22:43   ` Michael Ellerman

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