linux-kernel - Re: [PATCH] ARM: mvebu: declare asm symbols as character arrays in pmsu.c

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Date:   Thu, 28 Jun 2018 15:07:45 +0200
From:   Gregory CLEMENT <gregory.clement@...tlin.com>
To:     Ethan Tuttle <ethan@...antuttle.com>
Cc:     Andrew Lunn <andrew@...n.ch>, Jason Cooper <jason@...edaemon.net>,
        Russell King <linux@...linux.org.uk>,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>
Subject: Re: [PATCH] ARM: mvebu: declare asm symbols as character arrays in pmsu.c

Hi Ethan,

 On mer., juin 27 2018, Ethan Tuttle <ethan@...antuttle.com> wrote:

> Hi Gregory.
>
> On Tue, Jun 26, 2018 at 11:20 PM, Gregory CLEMENT
> <gregory.clement@...tlin.com> wrote:
>> Hi Ethan,
>>
>>  On mar., juin 19 2018, Ethan Tuttle <ethan@...antuttle.com> wrote:
>>
>>> With CONFIG_FORTIFY_SOURCE, memcpy uses the declared size of operands to
>>> detect buffer overflows.  If src or dest is declared as a char, attempts to
>>> copy more than byte will result in a fortify_panic().
>>>
>>> Address this problem in mvebu_setup_boot_addr_wa() by declaring
>>> mvebu_boot_wa_start and mvebu_boot_wa_end as character arrays.  Also remove
>>> a couple addressof operators to avoid "arithmetic on pointer to an
>>> incomplete type" compiler error.
>>>
>>> See commit 54a7d50b9205 ("x86: mark kprobe templates as character arrays,
>>> not single characters") for a similar fix.
>>>
>>> Fixes "detected buffer overflow in memcpy" error during init on some mvebu
>>> systems (armada-370-xp, armada-375):
>>>
>>> (fortify_panic) from (mvebu_setup_boot_addr_wa+0xb0/0xb4)
>>> (mvebu_setup_boot_addr_wa) from (mvebu_v7_cpu_pm_init+0x154/0x204)
>>> (mvebu_v7_cpu_pm_init) from (do_one_initcall+0x7c/0x1a8)
>>> (do_one_initcall) from (kernel_init_freeable+0x1bc/0x254)
>>> (kernel_init_freeable) from (kernel_init+0x8/0x114)
>>> (kernel_init) from (ret_from_fork+0x14/0x2c)
>>>
>>> Signed-off-by: Ethan Tuttle <ethan@...antuttle.com>
>>> Tested-by: Ethan Tuttle <ethan@...antuttle.com>
>>
>> Out of curiosity on which platform did you test it?
>
> I found the problem on my Mirabox after a kernel upgrade, and verified the fix
> on the Mirabox as well.
>
> I just observed in the code that the panic should also happen on armada-375,
> didn't do any testing there.
>
> BTW, just realizing I did not test with CONFIG_FORTIFY_SOURCE off.  But
> I imagine it will work.  Let me know if you think that requires
> testing.

No it's OK, thanks for extra information.

Gregory

>
>> Applied on mvebu/arm
>
> Excellent!  Thank you.
>
> Ethan
>
>>
>> Thanks,
>>
>> Gregory
>>
>>
>>
>>> ---
>>>  arch/arm/mach-mvebu/pmsu.c | 6 +++---
>>>  1 file changed, 3 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/arch/arm/mach-mvebu/pmsu.c b/arch/arm/mach-mvebu/pmsu.c
>>> index 27a78c80e5b1..73d5d72dfc3e 100644
>>> --- a/arch/arm/mach-mvebu/pmsu.c
>>> +++ b/arch/arm/mach-mvebu/pmsu.c
>>> @@ -116,8 +116,8 @@ void mvebu_pmsu_set_cpu_boot_addr(int hw_cpu, void *boot_addr)
>>>               PMSU_BOOT_ADDR_REDIRECT_OFFSET(hw_cpu));
>>>  }
>>>
>>> -extern unsigned char mvebu_boot_wa_start;
>>> -extern unsigned char mvebu_boot_wa_end;
>>> +extern unsigned char mvebu_boot_wa_start[];
>>> +extern unsigned char mvebu_boot_wa_end[];
>>>
>>>  /*
>>>   * This function sets up the boot address workaround needed for SMP
>>> @@ -130,7 +130,7 @@ int mvebu_setup_boot_addr_wa(unsigned int crypto_eng_target,
>>>                            phys_addr_t resume_addr_reg)
>>>  {
>>>       void __iomem *sram_virt_base;
>>> -     u32 code_len = &mvebu_boot_wa_end - &mvebu_boot_wa_start;
>>> +     u32 code_len = mvebu_boot_wa_end - mvebu_boot_wa_start;
>>>
>>>       mvebu_mbus_del_window(BOOTROM_BASE, BOOTROM_SIZE);
>>>       mvebu_mbus_add_window_by_id(crypto_eng_target, crypto_eng_attribute,
>>> --
>>> 2.17.1
>>>
>>>
>>> _______________________________________________
>>> linux-arm-kernel mailing list
>>> linux-arm-kernel@...ts.infradead.org
>>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>>
>> --
>> Gregory Clement, Bootlin (formerly Free Electrons)
>> Embedded Linux and Kernel engineering
>> http://bootlin.com

-- 
Gregory Clement, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
http://bootlin.com

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