From: "Steven Rostedt (Google)" <rost...@goodmis.org> As __assign_str() no longer uses its "src" parameter, there's a check to make sure nothing depends on it being different than what was passed to __string(). It originally just compared the pointer passed to __string() with the pointer passed into __assign_str() via the "src" parameter. But there's a couple of outliers that just pass in a quoted string constant, where comparing the pointers is UB to the compiler, as the compiler is free to create multiple copies of the same string constant.
Instead, just use strcmp(). It may slow down the trace event, but this will eventually be removed. Also, fix the issue of passing NULL to strcmp() by adding a WARN_ON() to make sure that both "src" and the pointer saved in __string() are either both NULL or have content, and then checking if "src" is not NULL before performing the strcmp(). Link: https://lore.kernel.org/all/CAHk-=wjxX16kWd=uxG5wzqt=axoydf1bgwokk+qvmao0zh7...@mail.gmail.com/ Fixes: b1afefa62ca9 ("tracing: Use strcmp() in __assign_str() WARN_ON() check") Reported-by: Linus Torvalds <torva...@linux-foundation.org> Signed-off-by: Steven Rostedt (Google) <rost...@goodmis.org> --- include/trace/stages/stage6_event_callback.h | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/include/trace/stages/stage6_event_callback.h b/include/trace/stages/stage6_event_callback.h index 83da83a0c14f..3690e677263f 100644 --- a/include/trace/stages/stage6_event_callback.h +++ b/include/trace/stages/stage6_event_callback.h @@ -35,9 +35,8 @@ do { \ char *__str__ = __get_str(dst); \ int __len__ = __get_dynamic_array_len(dst) - 1; \ - WARN_ON_ONCE(__builtin_constant_p(src) ? \ - strcmp((src), __data_offsets.dst##_ptr_) : \ - (src) != __data_offsets.dst##_ptr_); \ + WARN_ON_ONCE(!(void *)(src) != !(void *)__data_offsets.dst##_ptr_); \ + WARN_ON_ONCE((src) && strcmp((src), __data_offsets.dst##_ptr_)); \ memcpy(__str__, __data_offsets.dst##_ptr_ ? : \ EVENT_NULL_STR, __len__); \ __str__[__len__] = '\0'; \ -- 2.43.0
