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SubjectRe: [PATCH] trace-cmd: Don't SIGSEGV when event field format cannot be parsed.
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On Tue, 2010-07-13 at 11:44 -0700, David Daney wrote:
> >From the MIPS kernel we get things like:
>
> print fmt: "page=%p pfn=%lu order=%d migratetype=%d", REC->page, ({ struct page *__pg = (REC->page); int __sec = page_to_section(__pg); (unsigned long)(__pg - __section_mem_map_addr(__nr_to_section(__sec))); }), REC->order, REC->migratetype
>
> This cannot be parsed, leading to a NULL struct event_format* being
> passed to pevent_get_common_field_val, which produces a SIGSEGV. It
> would be good to get a parsable format from the kernel, but to
> remediate the problem for legacy kernels, we can just return an error
> indicator in this case. This allows some output from trace-cmd
> report, although perhaps with some missing data. But this is better
> than crashing.
>
> Signed-off-by: David Daney <ddaney@caviumnetworks.com>
> ---
> parse-events.c | 3 +++
> 1 files changed, 3 insertions(+), 0 deletions(-)
>
> diff --git a/parse-events.c b/parse-events.c
> index 9d5a3fa..16fff12 100644
> --- a/parse-events.c
> +++ b/parse-events.c
> @@ -4481,6 +4481,9 @@ int pevent_get_common_field_val(struct trace_seq *s, struct event_format *event,
> {

To be consistent, probably all the pevent_get_*field* should test for
null event.

Did you want to resend a patch that does that?

-- Steve

> struct format_field *field;
>
> + if (!event)
> + return -1;
> +
> field = pevent_find_common_field(event, name);
>
> return get_field_val(s, field, name, record, val, err);




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