linux-kernel - [PATCH 2/3] Revert "perf session: Avoid infinite loop when seeing invalid header.size"

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Date:   Tue, 24 Nov 2020 10:59:20 +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>,
        Tiezhu Yang <yangtiezhu@...ngson.cn>,
        Kan Liang <kan.liang@...ux.intel.com>,
        Alexey Budankov <alexey.budankov@...ux.intel.com>
Subject: [PATCH 2/3] Revert "perf session: Avoid infinite loop when seeing invalid header.size"

An event may be split by a buffer boundary, we should not abort processing
if that happens.

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 | 11 +----------
 1 file changed, 1 insertion(+), 10 deletions(-)

diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index 593d5a823eba..e57b0d09d196 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -1,7 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0
 #include <errno.h>
 #include <inttypes.h>
-#include <linux/err.h>
 #include <linux/kernel.h>
 #include <linux/zalloc.h>
 #include <api/fs/fs.h>
@@ -2045,9 +2044,7 @@ fetch_mmaped_event(struct perf_session *session,
 		/* 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);
+		return NULL;
 	}
 
 	return event;
@@ -2065,9 +2062,6 @@ static int __perf_session__process_decomp_events(struct perf_session *session)
 	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);
-
 		if (!event)
 			break;
 
@@ -2167,9 +2161,6 @@ reader__process_events(struct reader *rd, struct perf_session *session,
 
 more:
 	event = fetch_mmaped_event(session, head, mmap_size, buf);
-	if (IS_ERR(event))
-		return PTR_ERR(event);
-
 	if (!event) {
 		if (mmaps[map_idx]) {
 			munmap(mmaps[map_idx], mmap_size);
-- 
2.20.1