Avoid termination of trace loading in case the last record in
the decompressed buffer partly resides in the following
mmaped PERF_RECORD_COMPRESSED record. In this case NULL value
returned by fetch_mmaped_event() means to proceed to the next
mmaped record then decompress it and load compressed events.
The issue can be reproduced like this:
$ perf record -z -- some_long_running_workload
$ perf report --stdio -vv
decomp (B): 44519 to 163000
decomp (B): 48119 to 174800
decomp (B): 65527 to 131072
fetch_mmaped_event: head=0x1ffe0 event->header_size=0x28, mmap_size=0x20000: fuzzed perf.data?
Error:
failed to process sample
...
Testing:
71: Zstd perf.data compression/decompression : Ok
Fixes: 57fc032ad643 ("perf session: Avoid infinite loop when seeing invalid header.size")
Link: https://marc.info/?l=linux-kernel&m=156580812427554&w=2
Co-developed-by: Jiri Olsa <[email protected]>
Signed-off-by: Alexey Budankov <[email protected]>
---
tools/perf/util/session.c | 47 +++++++++++++++++++++++++++++++++--------------
1 file changed, 33 insertions(+), 14 deletions(-)
diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index f07b8ecb91bc..3f6f812ec4ed 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -1957,9 +1957,31 @@ static int __perf_session__process_pipe_events(struct perf_session *session)
return err;
}
+static union perf_event *
+prefetch_event(char *buf, u64 head, size_t mmap_size,
+ bool needs_swap, union perf_event *ret);
+
static union perf_event *
fetch_mmaped_event(struct perf_session *session,
u64 head, size_t mmap_size, char *buf)
+{
+ return prefetch_event(buf, head, mmap_size,
+ session->header.needs_swap,
+ ERR_PTR(-EINVAL));
+}
+
+static union perf_event *
+fetch_decomp_event(struct perf_session *session,
+ u64 head, size_t mmap_size, char *buf)
+{
+ return prefetch_event(buf, head, mmap_size,
+ session->header.needs_swap,
+ NULL);
+}
+
+static union perf_event *
+prefetch_event(char *buf, u64 head, size_t mmap_size,
+ bool needs_swap, union perf_event *ret)
{
union perf_event *event;
@@ -1971,20 +1993,20 @@ fetch_mmaped_event(struct perf_session *session,
return NULL;
event = (union perf_event *)(buf + head);
+ if (needs_swap)
+ perf_event_header__bswap(&event->header);
- if (session->header.needs_swap)
+ if (head + event->header.size <= mmap_size)
+ return event;
+
+ /* We're not fetching the event so swap back again */
+ if (needs_swap)
perf_event_header__bswap(&event->header);
- if (head + event->header.size > mmap_size) {
- /* We're not fetching the event so swap back again */
- if (session->header.needs_swap)
- perf_event_header__bswap(&event->header);
- pr_debug("%s: head=%#" PRIx64 " event->header_size=%#x, mmap_size=%#zx: fuzzed perf.data?\n",
- __func__, head, event->header.size, mmap_size);
- return ERR_PTR(-EINVAL);
- }
+ pr_debug("%s: head=%#" PRIx64 " event->header_size=%#x, mmap_size=%#zx\n",
+ __func__, head, event->header.size, mmap_size);
- return event;
+ return ret;
}
static int __perf_session__process_decomp_events(struct perf_session *session)
@@ -1997,10 +2019,7 @@ static int __perf_session__process_decomp_events(struct perf_session *session)
return 0;
while (decomp->head < decomp->size && !session_done()) {
- union perf_event *event = fetch_mmaped_event(session, decomp->head, decomp->size, decomp->data);
-
- if (IS_ERR(event))
- return PTR_ERR(event);
+ union perf_event *event = fetch_decomp_event(session, decomp->head, decomp->size, decomp->data);
if (!event)
break;
On Fri, Nov 15, 2019 at 12:05:14PM +0300, Alexey Budankov wrote:
>
> Avoid termination of trace loading in case the last record in
> the decompressed buffer partly resides in the following
> mmaped PERF_RECORD_COMPRESSED record. In this case NULL value
> returned by fetch_mmaped_event() means to proceed to the next
> mmaped record then decompress it and load compressed events.
>
> The issue can be reproduced like this:
>
> $ perf record -z -- some_long_running_workload
> $ perf report --stdio -vv
> decomp (B): 44519 to 163000
> decomp (B): 48119 to 174800
> decomp (B): 65527 to 131072
> fetch_mmaped_event: head=0x1ffe0 event->header_size=0x28, mmap_size=0x20000: fuzzed perf.data?
> Error:
> failed to process sample
> ...
>
> Testing:
> 71: Zstd perf.data compression/decompression : Ok
>
> Fixes: 57fc032ad643 ("perf session: Avoid infinite loop when seeing invalid header.size")
> Link: https://marc.info/?l=linux-kernel&m=156580812427554&w=2
> Co-developed-by: Jiri Olsa <[email protected]>
> Signed-off-by: Alexey Budankov <[email protected]>
> ---
> tools/perf/util/session.c | 47 +++++++++++++++++++++++++++++++++--------------
> 1 file changed, 33 insertions(+), 14 deletions(-)
>
> diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
> index f07b8ecb91bc..3f6f812ec4ed 100644
> --- a/tools/perf/util/session.c
> +++ b/tools/perf/util/session.c
> @@ -1957,9 +1957,31 @@ static int __perf_session__process_pipe_events(struct perf_session *session)
> return err;
> }
>
> +static union perf_event *
> +prefetch_event(char *buf, u64 head, size_t mmap_size,
> + bool needs_swap, union perf_event *ret);
why not move prefetch_event definition in here?
I don't see any need for the static declaration..
> +
> static union perf_event *
> fetch_mmaped_event(struct perf_session *session,
> u64 head, size_t mmap_size, char *buf)
> +{
> + return prefetch_event(buf, head, mmap_size,
> + session->header.needs_swap,
> + ERR_PTR(-EINVAL));
> +}
> +
> +static union perf_event *
> +fetch_decomp_event(struct perf_session *session,
> + u64 head, size_t mmap_size, char *buf)
> +{
if this is decomp specific, it could take 'struct decomp*' as argument
> + return prefetch_event(buf, head, mmap_size,
> + session->header.needs_swap,
> + NULL);
> +}
> +
> +static union perf_event *
> +prefetch_event(char *buf, u64 head, size_t mmap_size,
> + bool needs_swap, union perf_event *ret)
> {
'error' might be more suitable then ret in here
thanks,
jirka
On 15.11.2019 18:11, Jiri Olsa wrote:
> On Fri, Nov 15, 2019 at 12:05:14PM +0300, Alexey Budankov wrote:
<SNIP>
>> diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
>> index f07b8ecb91bc..3f6f812ec4ed 100644
>> --- a/tools/perf/util/session.c
>> +++ b/tools/perf/util/session.c
>> @@ -1957,9 +1957,31 @@ static int __perf_session__process_pipe_events(struct perf_session *session)
>> return err;
>> }
>>
>> +static union perf_event *
>> +prefetch_event(char *buf, u64 head, size_t mmap_size,
>> + bool needs_swap, union perf_event *ret);
>
> why not move prefetch_event definition in here?
> I don't see any need for the static declaration..
It is just for the sake of more readable patch formatting
and, yes, could be avoided and replaced by the definition.
>
>> +
>> static union perf_event *
>> fetch_mmaped_event(struct perf_session *session,
>> u64 head, size_t mmap_size, char *buf)
>> +{
>> + return prefetch_event(buf, head, mmap_size,
>> + session->header.needs_swap,
>> + ERR_PTR(-EINVAL));
>> +}
>> +
>> +static union perf_event *
>> +fetch_decomp_event(struct perf_session *session,
>> + u64 head, size_t mmap_size, char *buf)
>> +{
>
> if this is decomp specific, it could take 'struct decomp*' as argument
Well, it makes sense. whole session object is not required here.
Just session->header.needs_swap could be passed as a param.
Shall we make it like this?
static union perf_event *
fetch_decomp_event(u64 head, size_t mmap_size, char *buf, bool needs_swap)
>
>> + return prefetch_event(buf, head, mmap_size,
>> + session->header.needs_swap,
>> + NULL);
>> +}
>> +
>> +static union perf_event *
>> +prefetch_event(char *buf, u64 head, size_t mmap_size,
>> + bool needs_swap, union perf_event *ret)
>> {
>
> 'error' might be more suitable then ret in here
Accepted for v2.
~Alexey
>
> thanks,
> jirka
>
>
On Fri, Nov 15, 2019 at 08:09:19PM +0300, Alexey Budankov wrote:
>
> On 15.11.2019 18:11, Jiri Olsa wrote:
> > On Fri, Nov 15, 2019 at 12:05:14PM +0300, Alexey Budankov wrote:
> <SNIP>
> >> diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
> >> index f07b8ecb91bc..3f6f812ec4ed 100644
> >> --- a/tools/perf/util/session.c
> >> +++ b/tools/perf/util/session.c
> >> @@ -1957,9 +1957,31 @@ static int __perf_session__process_pipe_events(struct perf_session *session)
> >> return err;
> >> }
> >>
> >> +static union perf_event *
> >> +prefetch_event(char *buf, u64 head, size_t mmap_size,
> >> + bool needs_swap, union perf_event *ret);
> >
> > why not move prefetch_event definition in here?
> > I don't see any need for the static declaration..
>
> It is just for the sake of more readable patch formatting
> and, yes, could be avoided and replaced by the definition.
I think we're trying to avoid static declarations
>
> >
> >> +
> >> static union perf_event *
> >> fetch_mmaped_event(struct perf_session *session,
> >> u64 head, size_t mmap_size, char *buf)
> >> +{
> >> + return prefetch_event(buf, head, mmap_size,
> >> + session->header.needs_swap,
> >> + ERR_PTR(-EINVAL));
> >> +}
> >> +
> >> +static union perf_event *
> >> +fetch_decomp_event(struct perf_session *session,
> >> + u64 head, size_t mmap_size, char *buf)
> >> +{
> >
> > if this is decomp specific, it could take 'struct decomp*' as argument
>
> Well, it makes sense. whole session object is not required here.
> Just session->header.needs_swap could be passed as a param.
> Shall we make it like this?
>
> static union perf_event *
> fetch_decomp_event(u64 head, size_t mmap_size, char *buf, bool needs_swap)
ok, I just saw the call passing all the stuff from 'struct decomp'
so I thought it'd save some arguments if we pass the struct itself
instead
jirka