* [PATCH] perf: Avoid -Warray-bounds warning for __rel_loc macro
@ 2022-01-25 22:00 Kees Cook
2022-01-26 7:01 ` Masami Hiramatsu
0 siblings, 1 reply; 2+ messages in thread
From: Kees Cook @ 2022-01-25 22:00 UTC (permalink / raw)
To: Steven Rostedt
Cc: Kees Cook, Masami Hiramatsu, Stephen Rothwell, linux-next,
linux-kernel, linux-hardening
As done for trace_events.h, also fix the __rel_loc macro in perf.h,
which silences the -Warray-bounds warning:
In file included from ./include/linux/string.h:253,
from ./include/linux/bitmap.h:11,
from ./include/linux/cpumask.h:12,
from ./include/linux/mm_types_task.h:14,
from ./include/linux/mm_types.h:5,
from ./include/linux/buildid.h:5,
from ./include/linux/module.h:14,
from samples/trace_events/trace-events-sample.c:2:
In function '__fortify_strcpy',
inlined from 'perf_trace_foo_rel_loc' at samples/trace_events/./trace-events-sample.h:519:1:
./include/linux/fortify-string.h:47:33: warning: '__builtin_strcpy' offset 12 is out of the bounds [
0, 4] [-Warray-bounds]
47 | #define __underlying_strcpy __builtin_strcpy
| ^
./include/linux/fortify-string.h:445:24: note: in expansion of macro '__underlying_strcpy'
445 | return __underlying_strcpy(p, q);
| ^~~~~~~~~~~~~~~~~~~
Also make __data struct member a proper flexible array to avoid future
problems.
Cc: Steven Rostedt <rostedt@goodmis•org>
Cc: Masami Hiramatsu <mhiramat@kernel•org>
Reported-by: Stephen Rothwell <sfr@canb•auug.org.au>
Signed-off-by: Kees Cook <keescook@chromium•org>
---
include/trace/perf.h | 5 +++--
include/trace/trace_events.h | 2 +-
2 files changed, 4 insertions(+), 3 deletions(-)
diff --git a/include/trace/perf.h b/include/trace/perf.h
index b77d09c70a93..5800d13146c3 100644
--- a/include/trace/perf.h
+++ b/include/trace/perf.h
@@ -26,8 +26,9 @@
#undef __get_rel_dynamic_array
#define __get_rel_dynamic_array(field) \
- ((void *)(&__entry->__rel_loc_##field) + \
- sizeof(__entry->__rel_loc_##field) + \
+ ((void *)__entry + \
+ offsetof(typeof(*__entry), __rel_loc_##field) + \
+ sizeof(__entry->__rel_loc_##field) + \
(__entry->__rel_loc_##field & 0xffff))
#undef __get_rel_dynamic_array_len
diff --git a/include/trace/trace_events.h b/include/trace/trace_events.h
index cefefed18e85..7c86cc541c7a 100644
--- a/include/trace/trace_events.h
+++ b/include/trace/trace_events.h
@@ -134,7 +134,7 @@ TRACE_MAKE_SYSTEM_STR();
struct trace_event_raw_##name { \
struct trace_entry ent; \
tstruct \
- char __data[0]; \
+ char __data[]; \
}; \
\
static struct trace_event_class event_class_##name;
--
2.30.2
^ permalink raw reply related [flat|nested] 2+ messages in thread* Re: [PATCH] perf: Avoid -Warray-bounds warning for __rel_loc macro
2022-01-25 22:00 [PATCH] perf: Avoid -Warray-bounds warning for __rel_loc macro Kees Cook
@ 2022-01-26 7:01 ` Masami Hiramatsu
0 siblings, 0 replies; 2+ messages in thread
From: Masami Hiramatsu @ 2022-01-26 7:01 UTC (permalink / raw)
To: Kees Cook
Cc: Steven Rostedt, Masami Hiramatsu, Stephen Rothwell, linux-next,
linux-kernel, linux-hardening
On Tue, 25 Jan 2022 14:00:37 -0800
Kees Cook <keescook@chromium•org> wrote:
> As done for trace_events.h, also fix the __rel_loc macro in perf.h,
> which silences the -Warray-bounds warning:
>
> In file included from ./include/linux/string.h:253,
> from ./include/linux/bitmap.h:11,
> from ./include/linux/cpumask.h:12,
> from ./include/linux/mm_types_task.h:14,
> from ./include/linux/mm_types.h:5,
> from ./include/linux/buildid.h:5,
> from ./include/linux/module.h:14,
> from samples/trace_events/trace-events-sample.c:2:
> In function '__fortify_strcpy',
> inlined from 'perf_trace_foo_rel_loc' at samples/trace_events/./trace-events-sample.h:519:1:
> ./include/linux/fortify-string.h:47:33: warning: '__builtin_strcpy' offset 12 is out of the bounds [
> 0, 4] [-Warray-bounds]
> 47 | #define __underlying_strcpy __builtin_strcpy
> | ^
> ./include/linux/fortify-string.h:445:24: note: in expansion of macro '__underlying_strcpy'
> 445 | return __underlying_strcpy(p, q);
> | ^~~~~~~~~~~~~~~~~~~
>
> Also make __data struct member a proper flexible array to avoid future
> problems.
>
This looks good to me.
Reviewed-by: Masami Hiramatsu <mhiramat@kernel•org>
BTW, same macro is in the include/trace/bpf_probe.h.
I'm not sure bpf using this macro, should we update it for
consistency?
> Cc: Steven Rostedt <rostedt@goodmis•org>
> Cc: Masami Hiramatsu <mhiramat@kernel•org>
> Reported-by: Stephen Rothwell <sfr@canb•auug.org.au>
> Signed-off-by: Kees Cook <keescook@chromium•org>
> ---
> include/trace/perf.h | 5 +++--
> include/trace/trace_events.h | 2 +-
> 2 files changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/include/trace/perf.h b/include/trace/perf.h
> index b77d09c70a93..5800d13146c3 100644
> --- a/include/trace/perf.h
> +++ b/include/trace/perf.h
> @@ -26,8 +26,9 @@
>
> #undef __get_rel_dynamic_array
> #define __get_rel_dynamic_array(field) \
> - ((void *)(&__entry->__rel_loc_##field) + \
> - sizeof(__entry->__rel_loc_##field) + \
> + ((void *)__entry + \
> + offsetof(typeof(*__entry), __rel_loc_##field) + \
> + sizeof(__entry->__rel_loc_##field) + \
> (__entry->__rel_loc_##field & 0xffff))
>
> #undef __get_rel_dynamic_array_len
> diff --git a/include/trace/trace_events.h b/include/trace/trace_events.h
> index cefefed18e85..7c86cc541c7a 100644
> --- a/include/trace/trace_events.h
> +++ b/include/trace/trace_events.h
> @@ -134,7 +134,7 @@ TRACE_MAKE_SYSTEM_STR();
> struct trace_event_raw_##name { \
> struct trace_entry ent; \
> tstruct \
> - char __data[0]; \
> + char __data[]; \
> }; \
> \
> static struct trace_event_class event_class_##name;
> --
> 2.30.2
>
--
Masami Hiramatsu <mhiramat@kernel•org>
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