On Tue, 17 Aug 2021 23:05:20 -0700 Kees Cook <keescook@xxxxxxxxxxxx> wrote: > In preparation for FORTIFY_SOURCE performing compile-time and run-time > field bounds checking for memset(), avoid intentionally writing across > neighboring fields. > > Use memset_startat() to avoid confusing memset() about writing beyond > the target struct member. > > Cc: Steven Rostedt <rostedt@xxxxxxxxxxx> > Cc: Ingo Molnar <mingo@xxxxxxxxxx> > Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> > --- > kernel/trace/trace.c | 4 +--- > 1 file changed, 1 insertion(+), 3 deletions(-) > > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c > index 13587e771567..9ff8c31975cd 100644 > --- a/kernel/trace/trace.c > +++ b/kernel/trace/trace.c > @@ -6691,9 +6691,7 @@ tracing_read_pipe(struct file *filp, char __user *ubuf, > cnt = PAGE_SIZE - 1; > > /* reset all but tr, trace, and overruns */ > - memset(&iter->seq, 0, > - sizeof(struct trace_iterator) - > - offsetof(struct trace_iterator, seq)); > + memset_startat(iter, 0, seq); I can't find memset_startat() in mainline nor linux-next. I don't see it in this thread either, but since this has 63 patches, I could have easily missed it. This change really should belong to a patch set that just introduces memset_startat() (and perhaps memset_after()) and then updates all the places that should use it. That way I can give it a proper review. In other words, you should break this patch set up into smaller, more digestible portions for the reviewers. Thanks, -- Steve > cpumask_clear(iter->started); > trace_seq_init(&iter->seq); > iter->pos = -1;
