[PATCH] ARM: sun9i: smp: Fix array-index-out-of-bounds read in sunxi_mc_smp_init

[Stefan Wahren]

Hi Florian,

Am 24.12.23 um 11:12 schrieb Florian Fainelli:
>
>
> On 12/23/2023 1:35 PM, Stefan Wahren wrote:
>> Running a multi-arch kernel (multi_v7_defconfig) on a Raspberry Pi 3B+
>> with enabled CONFIG_UBSAN triggers the following warning:
>>
>>   UBSAN: array-index-out-of-bounds in
>> arch/arm/mach-sunxi/mc_smp.c:810:29
>>   index 2 is out of range for type 'sunxi_mc_smp_data [2]'
>>   CPU: 0 PID: 1 Comm: swapper/0 Not tainted
>> 6.7.0-rc6-00248-g5254c0cbc92d
>>   Hardware name: BCM2835
>>    unwind_backtrace from show_stack+0x10/0x14
>>    show_stack from dump_stack_lvl+0x40/0x4c
>>    dump_stack_lvl from ubsan_epilogue+0x8/0x34
>>    ubsan_epilogue from __ubsan_handle_out_of_bounds+0x78/0x80
>>    __ubsan_handle_out_of_bounds from sunxi_mc_smp_init+0xe4/0x4cc
>>    sunxi_mc_smp_init from do_one_initcall+0xa0/0x2fc
>>    do_one_initcall from kernel_init_freeable+0xf4/0x2f4
>>    kernel_init_freeable from kernel_init+0x18/0x158
>>    kernel_init from ret_from_fork+0x14/0x28
>>
>> Since the enabled method couldn't match with any entry from
>> sunxi_mc_smp_data, the value of the index shouldn't be used right after
>> the loop. So move it after the check of ret in order to have a valid
>> index.
>>
>> Fixes: 1631090e34f5 ("ARM: sun9i: smp: Add is_a83t field")
>> Signed-off-by: Stefan Wahren <wahrenst at gmx.net>
>
> Previous attempts at fixing this:
>
> https://lore.kernel.org/lkml/20230516-sunxi-v1-1-ac4b9651a8c1@google.com/T/
thanks for pointing out. Nick's version missed the refcounting of node
and my version missed the proper handling of of_property_match_string.
So we have actually two issues in the original code.

I will prepare a second version.

Nevertheless merry x-mas
>
> including a patch from William from nearly 18 months ago, which was
> not captured by lore however.
>
> Is anyone collecting patches for that platform still?