On Thu, 27 Mar 2025 11:32:23 -0700 Libo Chen <libo.c...@oracle.com> wrote:
> On 3/27/25 08:49, Steven Rostedt wrote: > > From: Steven Rostedt <rost...@goodmis.org> > > > > The trace event verifier checks the formats of trace events to make sure > > that they do not point at memory that is not in the trace event itself or > > in data that will never be freed. If an event references data that was > > allocated when the event triggered and that same data is freed before the > > event is read, then the kernel can crash by reading freed memory. > > > > The verifier runs at boot up (or module load) and scans the print formats > > of the events and checks their arguments to make sure that dereferenced > > pointers are safe. If the format uses "%*p.." the verifier will ignore it, > > and that could be dangerous. Cover this case as well. > > > > Also add to the sample code a use case of "%*pbl". > > > > Link: > > https://urldefense.com/v3/__https://lore.kernel.org/all/bcba4d76-2c3f-4d11-baf0-02905db95...@oracle.com/__;!!ACWV5N9M2RV99hQ!LTIVO1_O9wY2hBAnpNF5zcB1EFlC77zOnu4oVcM4DoD77p5ZO_m1LFZdPVJPj4spzye4JntXHOqOVxirPQ$ > > > > > Thanks Steve, a minor style issue below, otherwise LGTM. I have tested it, it > works. > > Reviewed-by: Libo Chen <libo.c...@oracle.com> > Tested-by: Libo Chen <libo.c...@oracle.com> Thanks for testing. > > /* > > * Notice here the use of some helper functions. This includes: > > @@ -370,7 +371,10 @@ TRACE_EVENT(foo_bar, > > > > __get_str(str), __get_str(lstr), > > __get_bitmask(cpus), __get_cpumask(cpum), > > - __get_str(vstr)) > > + __get_str(vstr), > > + __get_dynamic_array_len(cpus), > > + __get_dynamic_array_len(cpus), > > + __get_dynamic_array(cpus)) > > __get_dynamic_array_len() calls don't seem to be aligned with the ones above > Ah yeah. I'll update. Note, this isn't going to go into the kernel until at least 6.16. -- Steve
