spmi: trace: fix stack-out-of-bound access in SPMI tracing functions

In the Linux kernel, the following vulnerability has been resolved:

spmi: trace: fix stack-out-of-bound access in SPMI tracing functions

trace_spmi_write_begin() and trace_spmi_read_end() both call

memcpy() with a length of "len + 1". This leads to one extra

byte being read beyond the end of the specified buffer. Fix

this out-of-bound memory access by using a length of "len"

instead.

Here is a KASAN log showing the issue:

BUG: KASAN: stack-out-of-bounds in trace_event_raw_event_spmi_read_end+0x1d0/0x234

Read of size 2 at addr ffffffc0265b7540 by task [email protected]/1314

...

Call trace:

dump_backtrace+0x0/0x3e8

show_stack+0x2c/0x3c

dump_stack_lvl+0xdc/0x11c

print_address_description+0x74/0x384

kasan_report+0x188/0x268

kasan_check_range+0x270/0x2b0

memcpy+0x90/0xe8

trace_event_raw_event_spmi_read_end+0x1d0/0x234

spmi_read_cmd+0x294/0x3ac

spmi_ext_register_readl+0x84/0x9c

regmap_spmi_ext_read+0x144/0x1b0 [regmap_spmi]

_regmap_raw_read+0x40c/0x754

regmap_raw_read+0x3a0/0x514

regmap_bulk_read+0x418/0x494

adc5_gen3_poll_wait_hs+0xe8/0x1e0 [qcom_spmi_adc5_gen3]

...

__arm64_sys_read+0x4c/0x60

invoke_syscall+0x80/0x218

el0_svc_common+0xec/0x1c8

...

addr ffffffc0265b7540 is located in stack of task [email protected]/1314 at offset 32 in frame:

adc5_gen3_poll_wait_hs+0x0/0x1e0 [qcom_spmi_adc5_gen3]

this frame has 1 object:

[32, 33) 'status'

Memory state around the buggy address:

ffffffc0265b7400: 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1

ffffffc0265b7480: 04 f3 f3 f3 00 00 00 00 00 00 00 00 00 00 00 00

>ffffffc0265b7500: 00 00 00 00 f1 f1 f1 f1 01 f3 f3 f3 00 00 00 00

^

ffffffc0265b7580: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

ffffffc0265b7600: f1 f1 f1 f1 01 f2 07 f2 f2 f2 01 f3 00 00 00 00

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