Messages in this thread | | | Date | Thu, 1 Jun 2023 08:30:23 -0700 | From | Beau Belgrave <> | Subject | Re: [PATCH] tracing/user_events: Fix the incorrect trace record for null arguments events |
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On Thu, Jun 01, 2023 at 05:41:58PM +0800, sunliming wrote: > The user_events support events that has null arguments. But the trace event > is discard and not really committed when the arguments is null, fix this > problem. >
Thanks for the patch, this is a good catch! Can you reword this a bit? "fix this problem" could be reworded to "Fix this by not attempting to copy in non-zero data".
Would you mind adding this case to either the perf or ftrace self-test? It's a really good edge case.
Thanks, -Beau
> Signed-off-by: sunliming <sunliming@kylinos.cn> > --- > kernel/trace/trace_events_user.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/kernel/trace/trace_events_user.c b/kernel/trace/trace_events_user.c > index 0d91dac206ff..296bdfa674cb 100644 > --- a/kernel/trace/trace_events_user.c > +++ b/kernel/trace/trace_events_user.c > @@ -1399,7 +1399,7 @@ static void user_event_ftrace(struct user_event *user, struct iov_iter *i, > if (unlikely(!entry)) > return; > > - if (unlikely(!copy_nofault(entry + 1, i->count, i))) > + if (unlikely(i->count && !copy_nofault(entry + 1, i->count, i))) > goto discard; > > if (!list_empty(&user->validators) && > @@ -1440,7 +1440,7 @@ static void user_event_perf(struct user_event *user, struct iov_iter *i, > > perf_fetch_caller_regs(regs); > > - if (unlikely(!copy_nofault(perf_entry + 1, i->count, i))) > + if (unlikely(i->count && !copy_nofault(perf_entry + 1, i->count, i))) > goto discard; > > if (!list_empty(&user->validators) && > -- > 2.25.1
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