perf test: Add truncated perf.data robustness test

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 and fatal signals
  (KILL, 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:~#

Changes in v2:
- Add SIGKILL to the list of fatal signals so OOM kills from
  resource exhaustion bugs are detected (Reported-by: sashiko-bot@kernel.org)

Reviewed-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Assisted-by: Claude:claude-opus-4.6-1m
[ 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>

diff --git a/tools/perf/tests/shell/data_validation.sh b/tools/perf/tests/shell/data_validation.sh
new file mode 100755 (executable)
index 0000000..bf16b2f
--- /dev/null
+++ b/tools/perf/tests/shell/data_validation.sh
@@ -0,0 +1,86 @@
+#!/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() {
+       [ -n "${perfdata}" ] && rm -f "${perfdata}" "${perfdata}.old"
+       rm -f "${truncated}" "${stderrfile}"
+       trap - EXIT TERM INT
+}
+trap 'cleanup; exit 1' TERM INT
+trap cleanup EXIT
+
+perfdata=$(mktemp /tmp/__perf_test.perf.data.XXXXX) || exit 2
+truncated=$(mktemp /tmp/__perf_test.perf.data.XXXXX) || exit 2
+stderrfile=$(mktemp /tmp/__perf_test.perf.data.XXXXX) || exit 2
+
+# Record a simple workload
+if ! perf record -o "${perfdata}" -- perf test -w noploop 2>/dev/null; then
+       echo "Skip: perf record failed"
+       cleanup
+       exit 2
+fi
+
+file_size=$(wc -c < "${perfdata}")
+if [ "${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 "${file_size}" ]; then
+               continue
+       fi
+       dd if="${perfdata}" of="${truncated}" bs="${cut_at}" count=1 2>/dev/null
+
+       # 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 ${sig_name} in
+               KILL|ILL|ABRT|BUS|FPE|SEGV|TRAP|SYS)
+                       echo "FAIL: perf report crashed (SIG${sig_name}) on ${cut_at}-byte truncated file"
+                       err=1
+                       ;;
+               esac
+       fi
+done
+
+cleanup
+exit ${err}