From: Alexey Budankov alexey.budankov@linux.intel.com
[ Upstream commit bb1835a3b86c73aa534ef6430ad40223728dfbc0 ]
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
$ tools/perf/perf report -vv --stdio decomp (B): 59593 to 262160 decomp (B): 4438 to 16512 decomp (B): 285 to 880 Looking at the vmlinux_path (8 entries long) Using vmlinux for symbols decomp (B): 57474 to 261248 prefetch_event: head=0x3fc78 event->header_size=0x28, mmap_size=0x3fc80: fuzzed or compressed perf.data? decomp (B): 25 to 32 decomp (B): 52 to 120 ...
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 jolsa@kernel.org Acked-by: Jiri Olsa jolsa@kernel.org Signed-off-by: Alexey Budankov alexey.budankov@linux.intel.com Cc: Alexander Shishkin alexander.shishkin@linux.intel.com Cc: Andi Kleen ak@linux.intel.com Cc: Namhyung Kim namhyung@kernel.org Cc: Peter Zijlstra peterz@infradead.org Link: http://lore.kernel.org/lkml/cf782c34-f3f8-2f9f-d6ab-145cee0d5322@linux.intel... Signed-off-by: Arnaldo Carvalho de Melo acme@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- 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 061bb4d6a3f5a..5c172845fa5ac 100644 --- a/tools/perf/util/session.c +++ b/tools/perf/util/session.c @@ -1954,8 +1954,8 @@ 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;
@@ -1967,20 +1967,32 @@ 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:" + " fuzzed or compressed perf.data?\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) @@ -1993,10 +2005,8 @@ 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; @@ -2096,7 +2106,7 @@ 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);