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Subject[PATCH 01/28] perf session: Avoid infinite loop when seeing invalid header.size
Date
From: Arnaldo Carvalho de Melo <acme@redhat.com>

Vince reported that when fuzzing the userland perf tool with a bogus
perf.data file he got into a infinite loop in 'perf report'.

Changing the return of fetch_mmaped_event() to ERR_PTR(-EINVAL) for that
case gets us out of that infinite loop.

Reported-by: Vince Weaver <vincent.weaver@maine.edu>
Tested-by: Vince Weaver <vincent.weaver@maine.edu>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20190726211415.GE24867@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/util/session.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index 11e6093c941b..b9fe71d11bf6 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -1,6 +1,7 @@
// 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 <traceevent/event-parse.h>
@@ -1955,7 +1956,9 @@ 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);
- return NULL;
+ 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 event;
@@ -1973,6 +1976,9 @@ 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;

@@ -2072,6 +2078,9 @@ 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);
--
2.21.0
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