Re: [PATCH] tracing/uprobe: Fix to make trace_uprobe_filter alignment safe

[Masami Hiramatsu]

On Tue, 21 Jan 2020 10:50:55 -0500
Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:

> On Tue, 21 Jan 2020 16:46:19 +0900
> Masami Hiramatsu <mhiramat@xxxxxxxxxx> wrote:
> 
> > Commit 99c9a923e97a ("tracing/uprobe: Fix double perf_event
> > linking on multiprobe uprobe") moved trace_uprobe_filter on
> > trace_probe_event. However, since it introduced a flexible
> > data structure with char array and type casting, the
> > alignment of trace_uprobe_filter can be broken.
> > 
> > This changes the type of the array to trace_uprobe_filter
> > data strucure to fix it.
> > 
> > Fixes: 99c9a923e97a ("tracing/uprobe: Fix double perf_event linking on multiprobe uprobe")
> > Suggested-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> > Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
> > ---
> >  kernel/trace/trace_kprobe.c |    2 +-
> >  kernel/trace/trace_probe.c  |    9 ++++++---
> >  kernel/trace/trace_probe.h  |   10 ++++++++--
> >  kernel/trace/trace_uprobe.c |   29 +++++++----------------------
> >  4 files changed, 22 insertions(+), 28 deletions(-)
> 
> 
> I hit the following build error with this:

Hmm, I missed something... let me check and update it.

Thank you,

> 
> /work/git/linux-trace.git/kernel/trace/trace_uprobe.c: In function ‘alloc_trace_uprobe’:
> /work/git/linux-trace.git/kernel/trace/trace_uprobe.c:355:39: error: ‘tu->tp.event’ is a pointer; did you mean to use ‘->’?
>   init_trace_uprobe_filter(tu->tp.event.filter);
>                                        ^
>                                        ->
> In file included from /work/git/linux-trace.git/arch/x86/include/asm/bug.h:83,
>                  from /work/git/linux-trace.git/include/linux/bug.h:5,
>                  from /work/git/linux-trace.git/arch/x86/include/asm/paravirt.h:15,
>                  from /work/git/linux-trace.git/arch/x86/include/asm/irqflags.h:72,
>                  from /work/git/linux-trace.git/include/linux/irqflags.h:16,
>                  from /work/git/linux-trace.git/include/linux/rcupdate.h:26,
>                  from /work/git/linux-trace.git/include/linux/rbtree.h:22,
>                  from /work/git/linux-trace.git/include/linux/key.h:15,
>                  from /work/git/linux-trace.git/include/linux/security.h:26,
>                  from /work/git/linux-trace.git/kernel/trace/trace_uprobe.c:10:
> /work/git/linux-trace.git/kernel/trace/trace_uprobe.c: In function ‘__probe_event_disable’:
> /work/git/linux-trace.git/kernel/trace/trace_uprobe.c:1064:46: error: ‘tu->tp.event’ is a pointer; did you mean to use ‘->’?
>   WARN_ON(!uprobe_filter_is_empty(tu->tp.event.filter));
>                                               ^
> /work/git/linux-trace.git/include/asm-generic/bug.h:113:25: note: in definition of macro ‘WARN_ON’
>   int __ret_warn_on = !!(condition);    \
>                          ^~~~~~~~~
> /work/git/linux-trace.git/kernel/trace/trace_uprobe.c: In function ‘probe_event_enable’:
> /work/git/linux-trace.git/kernel/trace/trace_uprobe.c:1105:46: error: ‘tu->tp.event’ is a pointer; did you mean to use ‘->’?
>   WARN_ON(!uprobe_filter_is_empty(tu->tp.event.filter));
>                                               ^
> /work/git/linux-trace.git/include/asm-generic/bug.h:113:25: note: in definition of macro ‘WARN_ON’
>   int __ret_warn_on = !!(condition);    \
>                          ^~~~~~~~~
> /work/git/linux-trace.git/kernel/trace/trace_uprobe.c: In function ‘uprobe_perf_close’:
> /work/git/linux-trace.git/kernel/trace/trace_uprobe.c:1269:45: error: ‘tu->tp.event’ is a pointer; did you mean to use ‘->’?
>   if (trace_uprobe_filter_remove(tu->tp.event.filter, event))
>                                              ^
>                                              ->
> /work/git/linux-trace.git/kernel/trace/trace_uprobe.c: In function ‘uprobe_perf_open’:
> /work/git/linux-trace.git/kernel/trace/trace_uprobe.c:1294:42: error: ‘tu->tp.event’ is a pointer; did you mean to use ‘->’?
>   if (trace_uprobe_filter_add(tu->tp.event.filter, event))
>                                           ^
>                                           ->
> /work/git/linux-trace.git/kernel/trace/trace_uprobe.c: In function ‘uprobe_perf_filter’:
> /work/git/linux-trace.git/kernel/trace/trace_uprobe.c:1316:23: error: ‘tu->tp.event’ is a pointer; did you mean to use ‘->’?
>   filter = tu->tp.event.filter;
>                        ^
>                        ->
> make[3]: *** [/work/git/linux-trace.git/scripts/Makefile.build:266: kernel/trace/trace_uprobe.o] Error 1
> make[3]: *** Waiting for unfinished jobs....
> 
> 
> Config attached.
> 
> -- Steve


-- 
Masami Hiramatsu <mhiramat@xxxxxxxxxx>