Hi Steve, I don't think this needs to be backported to stable, since the only place that uses the high 16 bits of the offset field as the length is filter_pred_strloc which only works for strings and sizeof(char) == 1 so that essentially whenever the bug is triggered, the actual stored value is not used.
I have a follow up patch to expose that field to TP_fast_assign (as something like __get_dynamic_array_length) in which case it's important that this is fixed, otherwise for __dynamic_array of something other than char we'll have a bug. Thanks, Filipe On Mon, Mar 3, 2014 at 11:51 AM, Steven Rostedt <[email protected]> wrote: > On Fri, 28 Feb 2014 21:32:16 -0800 > Filipe Brandenburger <[email protected]> wrote: > >> This fixes expansion of the len argument in __dynamic_array macros. >> The previous code from commit 7d536cb3f would not fully evaluate the >> expression before multiplying its result by the size of the type. >> >> This went unnoticed because the length stored in the high 16 bits of the >> offset (which is the one that was broken here) is only used by >> filter_pred_strloc which only acts on strings for which the size of the >> type is 1. >> > > Was this visible in any of the tracepoints? Should this be marked for > stable? It's been in the kernel for a long time (2009). Or is a new > tracepoint showing a problem? > > -- Steve > >> Signed-off-by: Filipe Brandenburger <[email protected]> >> --- >> include/trace/ftrace.h | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h >> index 1a8b28d..82e8d89 100644 >> --- a/include/trace/ftrace.h >> +++ b/include/trace/ftrace.h >> @@ -375,7 +375,7 @@ ftrace_define_fields_##call(struct ftrace_event_call >> *event_call) \ >> #define __dynamic_array(type, item, len) \ >> __data_offsets->item = __data_size + \ >> offsetof(typeof(*entry), __data); \ >> - __data_offsets->item |= (len * sizeof(type)) << 16; \ >> + __data_offsets->item |= ((len) * sizeof(type)) << 16; \ >> __data_size += (len) * sizeof(type); >> >> #undef __string > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
