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]>
---
Changes in v2:
- avoided static declaration of prefetch_event();
- renamed 'ret' to 'error' for returning in case of split compressed
or overlapping records;
- passed only needs_swap quality into fetch_*_event() instead of
the whole session object;
---
tools/perf/util/session.c | 44 ++++++++++++++++++++++++---------------
1 file changed, 27 insertions(+), 17 deletions(-)
diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index f07b8ecb91bc..c2b0703d6587 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -1958,8 +1958,8 @@ static int __perf_session__process_pipe_events(struct perf_session *session)
}
static union perf_event *
-fetch_mmaped_event(struct perf_session *session,
- u64 head, size_t mmap_size, char *buf)
+prefetch_event(char *buf, u64 head, size_t mmap_size,
+ bool needs_swap, union perf_event *error)
{
union perf_event *event;
@@ -1971,20 +1971,32 @@ 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 error;
+}
+
+static union perf_event *
+fetch_mmaped_event(u64 head, size_t mmap_size, char *buf, bool needs_swap)
+{
+ return prefetch_event(buf, head, mmap_size, needs_swap, ERR_PTR(-EINVAL));
+}
+
+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, needs_swap, NULL);
}
static int __perf_session__process_decomp_events(struct perf_session *session)
@@ -1997,10 +2009,8 @@ 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(decomp->head, decomp->size, decomp->data,
+ session->header.needs_swap);
if (!event)
break;
@@ -2100,7 +2110,7 @@ reader__process_events(struct reader *rd, struct perf_session *session,
}
more:
- event = fetch_mmaped_event(session, head, mmap_size, buf);
+ event = fetch_mmaped_event(head, mmap_size, buf, session->header.needs_swap);
if (IS_ERR(event))
return PTR_ERR(event);
--
2.20.1
On Mon, Nov 18, 2019 at 02:30:04PM +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]>
> ---
> Changes in v2:
> - avoided static declaration of prefetch_event();
> - renamed 'ret' to 'error' for returning in case of split compressed
> or overlapping records;
> - passed only needs_swap quality into fetch_*_event() instead of
> the whole session object;
> ---
> tools/perf/util/session.c | 44 ++++++++++++++++++++++++---------------
> 1 file changed, 27 insertions(+), 17 deletions(-)
>
> diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
> index f07b8ecb91bc..c2b0703d6587 100644
> --- a/tools/perf/util/session.c
> +++ b/tools/perf/util/session.c
> @@ -1958,8 +1958,8 @@ static int __perf_session__process_pipe_events(struct perf_session *session)
> }
>
> static union perf_event *
> -fetch_mmaped_event(struct perf_session *session,
> - u64 head, size_t mmap_size, char *buf)
> +prefetch_event(char *buf, u64 head, size_t mmap_size,
> + bool needs_swap, union perf_event *error)
> {
> union perf_event *event;
>
> @@ -1971,20 +1971,32 @@ 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);
you're missign the 'fuzzed perf.data?' in here
I think we should keep it just change to: 'fuzzed or compressed perf.data?'
thanks,
jirka
On 18.11.2019 15:22, Jiri Olsa wrote:
> On Mon, Nov 18, 2019 at 02:30:04PM +0300, Alexey Budankov wrote:
<SNIP>
>>
>> @@ -1971,20 +1971,32 @@ 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);
>
> you're missign the 'fuzzed perf.data?' in here
>
> I think we should keep it just change to: 'fuzzed or compressed perf.data?'
Fixed in v3.
>
> thanks,
> jirka
~Alexey