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

[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/

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?
-- 
Florian