linux-kernel - [PATCH 1/3] Revert "perf session: Fix decompression of PERF_RECORD

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Date:   Tue, 24 Nov 2020 10:59:19 +0100
From:   Petr Malat <oss@...at.biz>
To:     linux-kernel@...r.kernel.org
Cc:     Petr Malat <oss@...at.biz>, Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Kan Liang <kan.liang@...ux.intel.com>,
        Alexey Budankov <alexey.budankov@...ux.intel.com>
Subject: [PATCH 1/3] Revert "perf session: Fix decompression of PERF_RECORD_COMPRESSED records"

Both mmapped and compressed events can be split by the buffer boundary,
it doesn't make sense to handle them differently.

Fixes: bb1835a3b86c ("perf session: Fix decompression of PERF_RECORD_COMPRESSED records")
Fixes: 57fc032ad643 ("perf session: Avoid infinite loop when seeing invalid header.size")
Signed-off-by: Petr Malat <oss@...at.biz>
---
 tools/perf/util/session.c | 44 +++++++++++++++------------------------
 1 file changed, 17 insertions(+), 27 deletions(-)

diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index 7a5f03764702..593d5a823eba 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -2024,8 +2024,8 @@ static int __perf_session__process_pipe_events(struct perf_session *session)
 }
 
 static union perf_event *
-prefetch_event(char *buf, u64 head, size_t mmap_size,
-	       bool needs_swap, union perf_event *error)
+fetch_mmaped_event(struct perf_session *session,
+		   u64 head, size_t mmap_size, char *buf)
 {
 	union perf_event *event;
 
@@ -2037,32 +2037,20 @@ prefetch_event(char *buf, u64 head, size_t mmap_size,
 		return NULL;
 
 	event = (union perf_event *)(buf + head);
-	if (needs_swap)
-		perf_event_header__bswap(&event->header);
-
-	if (head + event->header.size <= mmap_size)
-		return event;
 
-	/* We're not fetching the event so swap back again */
-	if (needs_swap)
+	if (session->header.needs_swap)
 		perf_event_header__bswap(&event->header);
 
-	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 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));
-}
+	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);
+	}
 
-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);
+	return event;
 }
 
 static int __perf_session__process_decomp_events(struct perf_session *session)
@@ -2075,8 +2063,10 @@ 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_decomp_event(decomp->head, decomp->size, decomp->data,
-							     session->header.needs_swap);
+		union perf_event *event = fetch_mmaped_event(session, decomp->head, decomp->size, decomp->data);
+
+		if (IS_ERR(event))
+			return PTR_ERR(event);
 
 		if (!event)
 			break;
@@ -2176,7 +2166,7 @@ reader__process_events(struct reader *rd, struct perf_session *session,
 	}
 
 more:
-	event = fetch_mmaped_event(head, mmap_size, buf, session->header.needs_swap);
+	event = fetch_mmaped_event(session, head, mmap_size, buf);
 	if (IS_ERR(event))
 		return PTR_ERR(event);
 
-- 
2.20.1