* [PATCH] perf synthetic events: Avoid write of uninitialized memory.
@ 2021-03-09 23:49 Ian Rogers
2021-03-10 11:48 ` Jiri Olsa
0 siblings, 1 reply; 3+ messages in thread
From: Ian Rogers @ 2021-03-09 23:49 UTC (permalink / raw)
To: Peter Zijlstra, Ingo Molnar, Arnaldo Carvalho de Melo,
Mark Rutland, Alexander Shishkin, Jiri Olsa, Namhyung Kim,
linux-kernel
Cc: Stephane Eranian, Ian Rogers
Account for alignment bytes in the zero-ing memset.
Signed-off-by: Ian Rogers <irogers@google.com>
---
tools/perf/util/synthetic-events.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c
index b698046ec2db..31bf3dd6a1e0 100644
--- a/tools/perf/util/synthetic-events.c
+++ b/tools/perf/util/synthetic-events.c
@@ -424,7 +424,7 @@ int perf_event__synthesize_mmap_events(struct perf_tool *tool,
while (!io.eof) {
static const char anonstr[] = "//anon";
- size_t size;
+ size_t size, aligned_size;
/* ensure null termination since stack will be reused. */
event->mmap2.filename[0] = '\0';
@@ -484,11 +484,12 @@ int perf_event__synthesize_mmap_events(struct perf_tool *tool,
}
size = strlen(event->mmap2.filename) + 1;
- size = PERF_ALIGN(size, sizeof(u64));
+ aligned_size = PERF_ALIGN(size, sizeof(u64));
event->mmap2.len -= event->mmap.start;
event->mmap2.header.size = (sizeof(event->mmap2) -
- (sizeof(event->mmap2.filename) - size));
- memset(event->mmap2.filename + size, 0, machine->id_hdr_size);
+ (sizeof(event->mmap2.filename) - aligned_size));
+ memset(event->mmap2.filename + size, 0, machine->id_hdr_size +
+ (aligned_size - size));
event->mmap2.header.size += machine->id_hdr_size;
event->mmap2.pid = tgid;
event->mmap2.tid = pid;
--
2.30.1.766.gb4fecdf3b7-goog
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] perf synthetic events: Avoid write of uninitialized memory.
2021-03-09 23:49 [PATCH] perf synthetic events: Avoid write of uninitialized memory Ian Rogers
@ 2021-03-10 11:48 ` Jiri Olsa
2021-03-10 13:13 ` Arnaldo Carvalho de Melo
0 siblings, 1 reply; 3+ messages in thread
From: Jiri Olsa @ 2021-03-10 11:48 UTC (permalink / raw)
To: Ian Rogers
Cc: Peter Zijlstra, Ingo Molnar, Arnaldo Carvalho de Melo,
Mark Rutland, Alexander Shishkin, Namhyung Kim, linux-kernel,
Stephane Eranian
On Tue, Mar 09, 2021 at 03:49:45PM -0800, Ian Rogers wrote:
> Account for alignment bytes in the zero-ing memset.
>
> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
> tools/perf/util/synthetic-events.c | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c
> index b698046ec2db..31bf3dd6a1e0 100644
> --- a/tools/perf/util/synthetic-events.c
> +++ b/tools/perf/util/synthetic-events.c
> @@ -424,7 +424,7 @@ int perf_event__synthesize_mmap_events(struct perf_tool *tool,
>
> while (!io.eof) {
> static const char anonstr[] = "//anon";
> - size_t size;
> + size_t size, aligned_size;
>
> /* ensure null termination since stack will be reused. */
> event->mmap2.filename[0] = '\0';
> @@ -484,11 +484,12 @@ int perf_event__synthesize_mmap_events(struct perf_tool *tool,
> }
>
> size = strlen(event->mmap2.filename) + 1;
> - size = PERF_ALIGN(size, sizeof(u64));
> + aligned_size = PERF_ALIGN(size, sizeof(u64));
> event->mmap2.len -= event->mmap.start;
> event->mmap2.header.size = (sizeof(event->mmap2) -
> - (sizeof(event->mmap2.filename) - size));
> - memset(event->mmap2.filename + size, 0, machine->id_hdr_size);
> + (sizeof(event->mmap2.filename) - aligned_size));
> + memset(event->mmap2.filename + size, 0, machine->id_hdr_size +
> + (aligned_size - size));
so we did not zero the extra alignment bytes, nice ;-) looks good
Acked-by: Jiri Olsa <jolsa@redhat.com>
thanks,
jirka
> event->mmap2.header.size += machine->id_hdr_size;
> event->mmap2.pid = tgid;
> event->mmap2.tid = pid;
> --
> 2.30.1.766.gb4fecdf3b7-goog
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] perf synthetic events: Avoid write of uninitialized memory.
2021-03-10 11:48 ` Jiri Olsa
@ 2021-03-10 13:13 ` Arnaldo Carvalho de Melo
0 siblings, 0 replies; 3+ messages in thread
From: Arnaldo Carvalho de Melo @ 2021-03-10 13:13 UTC (permalink / raw)
To: Jiri Olsa
Cc: Ian Rogers, Peter Zijlstra, Ingo Molnar, Mark Rutland,
Alexander Shishkin, Namhyung Kim, linux-kernel, Stephane Eranian
Em Wed, Mar 10, 2021 at 12:48:36PM +0100, Jiri Olsa escreveu:
> On Tue, Mar 09, 2021 at 03:49:45PM -0800, Ian Rogers wrote:
> > Account for alignment bytes in the zero-ing memset.
> >
> > Signed-off-by: Ian Rogers <irogers@google.com>
> > ---
> > tools/perf/util/synthetic-events.c | 9 +++++----
> > 1 file changed, 5 insertions(+), 4 deletions(-)
> >
> > diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c
> > index b698046ec2db..31bf3dd6a1e0 100644
> > --- a/tools/perf/util/synthetic-events.c
> > +++ b/tools/perf/util/synthetic-events.c
> > @@ -424,7 +424,7 @@ int perf_event__synthesize_mmap_events(struct perf_tool *tool,
> >
> > while (!io.eof) {
> > static const char anonstr[] = "//anon";
> > - size_t size;
> > + size_t size, aligned_size;
> >
> > /* ensure null termination since stack will be reused. */
> > event->mmap2.filename[0] = '\0';
> > @@ -484,11 +484,12 @@ int perf_event__synthesize_mmap_events(struct perf_tool *tool,
> > }
> >
> > size = strlen(event->mmap2.filename) + 1;
> > - size = PERF_ALIGN(size, sizeof(u64));
> > + aligned_size = PERF_ALIGN(size, sizeof(u64));
> > event->mmap2.len -= event->mmap.start;
> > event->mmap2.header.size = (sizeof(event->mmap2) -
> > - (sizeof(event->mmap2.filename) - size));
> > - memset(event->mmap2.filename + size, 0, machine->id_hdr_size);
> > + (sizeof(event->mmap2.filename) - aligned_size));
> > + memset(event->mmap2.filename + size, 0, machine->id_hdr_size +
> > + (aligned_size - size));
>
> so we did not zero the extra alignment bytes, nice ;-) looks good
>
> Acked-by: Jiri Olsa <jolsa@redhat.com>
That is really old:
Fixes: 1a853e36871b533c ("perf record: Allow specifying a pid to record")
Circa 2009, the PERF_RECORD_COMM is ok as TASK_COMM_LEN is 16.
But I think there are other places synthesizing PERF_RECORD_MMAP,
jitdump maybe:
tools/perf/bench/inject-buildid.c, but it uses memset to zero the whole
union, no problem.
tools/perf/util/jitdump.c
jit_repipe_code_load() but it uses calloc to allocate the union
perf_event, so no problem as well.
Thanks, applied.
- Arnaldo
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2021-03-09 23:49 [PATCH] perf synthetic events: Avoid write of uninitialized memory Ian Rogers
2021-03-10 11:48 ` Jiri Olsa
2021-03-10 13:13 ` Arnaldo Carvalho de Melo
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