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

[ Upstream commit 72ad3b77 ]

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: 1631090e ("ARM: sun9i: smp: Add is_a83t field")
Signed-off-by: Stefan Wahren <wahrenst@gmx.net>
Link: https://lore.kernel.org/r/20231228193903.9078-1-wahrenst@gmx.net


Reviewed-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>