[PATCH 27/27] perf test: Add truncated perf.data robustness test

[Arnaldo Carvalho de Melo <acme@kernel.org>]

From: Arnaldo Carvalho de Melo <acme@redhat.com>

Add a shell test that verifies perf report handles truncated perf.data
files gracefully — exiting with an error code rather than crashing with
SIGSEGV or SIGABRT.

The test records a simple workload, then truncates the resulting
perf.data at four offsets that exercise different parsing stages:

  8 bytes   — file header magic only
  64 bytes  — partial file header (attr section incomplete)
  256 bytes — into the first events (partial event headers)
  75% size  — mid-stream truncation (partial event data)

For each truncation, perf report is run and the exit code is checked:

- Exit code 0 (success) fails the test — a truncated file should
  never parse without error.

- Crash signals are detected portably via kill -l, which maps the
  signal number to a name on the running system.  This handles
  architectures where signal numbers differ (e.g. SIGBUS is 7 on
  x86/ARM but 10 on MIPS/SPARC).  Core-dump signals (ILL, ABRT,
  BUS, FPE, SEGV, TRAP, SYS) fail the test.

- Higher exit codes (200+) are perf's own negative-errno returns
  (e.g. -EINVAL = 234) and are expected.

This exercises the bounds checking, minimum-size validation, and error
propagation added by the preceding patches in this series.

Testing it:

  root@number:~# perf test truncat
   84: Test that perf report handles truncated perf.data gracefully (no crash, no segfault — clean error exit).: Ok
  root@number:~# perf test -vv truncat
   84: Test that perf report handles truncated perf.data gracefully (no crash, no segfault — clean error exit).:
  --- start ---
  test child forked, pid 62890
  ---- end(0) ----
   84: Test that perf report handles truncated perf.data gracefully (no crash, no segfault — clean error exit).: Ok
  root@number:~#

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Assisted-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
[ Fixed the SPDX on the line where 'perf test' expects the test description, reviewed by Ian Rogers ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/tests/shell/data_validation.sh | 85 +++++++++++++++++++++++
 1 file changed, 85 insertions(+)
 create mode 100755 tools/perf/tests/shell/data_validation.sh

diff --git a/tools/perf/tests/shell/data_validation.sh b/tools/perf/tests/shell/data_validation.sh
new file mode 100755
index 0000000000000000..fa7980c4ddd30954
--- /dev/null
+++ b/tools/perf/tests/shell/data_validation.sh
@@ -0,0 +1,85 @@
+#!/bin/bash
+# Test that perf report handles truncated perf.data gracefully (no crash, no segfault — clean error exit).
+# SPDX-License-Identifier: GPL-2.0
+#
+# Exercises the bounds checking and minimum-size validation added
+# by the perf-data-validation hardening series.
+
+err=0
+
+cleanup() {
+	rm -f "${perfdata}" "${perfdata}.old" "${truncated}" "${stderrfile}"
+	trap - EXIT TERM INT
+}
+trap 'cleanup; exit 1' TERM INT
+trap cleanup EXIT
+
+perfdata=$(mktemp /tmp/__perf_test.perf.data.XXXXX)
+truncated=$(mktemp /tmp/__perf_test.perf.data.XXXXX)
+stderrfile=$(mktemp /tmp/__perf_test.perf.data.XXXXX)
+
+# Record a simple workload
+if ! perf record -o "${perfdata}" -- perf test -w noploop 2>/dev/null; then
+	echo "Skip: perf record failed"
+	cleanup
+	exit 2
+fi
+
+file_size=$(stat -c %s "${perfdata}")
+if [ "${file_size}" -lt 512 ]; then
+	echo "Skip: perf.data too small (${file_size} bytes)"
+	cleanup
+	exit 2
+fi
+
+# Test truncation at various offsets that exercise different
+# parsing stages:
+#   8    — file header magic only, no attrs or data
+#   64   — partial file header (attr section incomplete)
+#   256  — into the first events (partial event headers)
+#   75%  — mid-stream truncation (partial event data)
+for cut_at in 8 64 256 $((file_size * 3 / 4)); do
+	if [ "${cut_at}" -ge "${file_size}" ]; then
+		continue
+	fi
+	head -c "${cut_at}" "${perfdata}" > "${truncated}"
+
+	# perf report should exit with an error, not crash.
+	# Capture stderr to detect sanitizer violations.
+	perf report -i "${truncated}" --stdio > /dev/null 2> "${stderrfile}"
+	exit_code=$?
+
+	# A truncated file should never parse successfully
+	if [ ${exit_code} -eq 0 ]; then
+		echo "FAIL: perf report exited 0 (success) on ${cut_at}-byte truncated file — expected an error"
+		err=1
+		continue
+	fi
+
+	# Detect sanitizer violations — ASAN/MSAN/TSAN/UBSAN exit
+	# with code 1 by default, which would otherwise look like a
+	# clean error exit.  Check stderr for their markers.
+	if grep -qE "^(==[0-9]+==ERROR:|SUMMARY: [A-Za-z]*Sanitizer)" "${stderrfile}" 2>/dev/null; then
+		sanitizer=$(grep -oE "(Address|Memory|Thread|UndefinedBehavior)Sanitizer" "${stderrfile}" | head -1)
+		echo "FAIL: perf report triggered ${sanitizer:-sanitizer} on ${cut_at}-byte truncated file"
+		err=1
+		continue
+	fi
+
+	# Detect crash signals portably — signal numbers differ
+	# across architectures (e.g. SIGBUS is 7 on x86/ARM but
+	# 10 on MIPS/SPARC).  Use kill -l to map the number to a
+	# name on the running system.
+	if [ ${exit_code} -gt 128 ] && [ ${exit_code} -lt 200 ]; then
+		sig_name=$(kill -l $((exit_code - 128)) 2>/dev/null)
+		case ${sig_name} in
+		ILL|ABRT|BUS|FPE|SEGV|TRAP|SYS)
+			echo "FAIL: perf report crashed (SIG${sig_name}) on ${cut_at}-byte truncated file"
+			err=1
+			;;
+		esac
+	fi
+done
+
+cleanup
+exit ${err}
-- 
2.54.0