Re: [PATCH] spmi: trace: fix stack-out-of-bound access in SPMI tracing functions

[Stephen Boyd]

Quoting David Collins (2022-06-27 16:55:12)
> 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 thermal@2.0-ser/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 thermal@2.0-ser/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
> ==================================================================
> 
> Fixes: a9fce374815d ("spmi: add command tracepoints for SPMI")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: David Collins <quic_collinsd@xxxxxxxxxxx>
> ---

Reviewed-by: Stephen Boyd <sboyd@xxxxxxxxxx>

Greg, can you pick this up directly? I don't have anything else for this
cycle.