Re: [PATCH v1 05/12] perf tests: Skip metrics validation if system-wide recording lacks permission

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Critical] Insecure temporary file creation allows arbitrary file overwrite via symlink attack.
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commit c60696a6dd47d2ab5c2a513da9f459f6cbd7d660
Author: Ian Rogers <irogers@google.com>

perf tests: Add robust record retry helper and use subsecond workloads

This commit introduces a shared library helper, perf_record_with_retry, to
prevent record test failures caused by transient recording or workload delays.
It updates several test scripts to use this robust retry logic. The tests now
start with very short durations and scale up if the initial recording fails.

> diff --git a/tools/perf/tests/shell/lib/perf_record.sh b/tools/perf/tests/shell/lib/perf_record.sh
> new file mode 100644
> index 0000000000000..c5de252447705
> --- /dev/null
> +++ b/tools/perf/tests/shell/lib/perf_record.sh
> @@ -0,0 +1,47 @@
> +# SPDX-License-Identifier: GPL-2.0
> +
> +perf_record_with_retry() {
> +  local perfdata="$1"
> +  local check_cmd="$2"
> +  local testprog_base="$3"
> +  shift 3
> +
> +  local logfile
> +  logfile="/tmp/__perf_record_retry.$(id -u).$BASHPID.log"
> +
> +  # Save the e flag state and disable it
> +  local save_e
> +  if [[ $- == *e* ]]; then
> +    save_e="set -e"
> +  else
> +    save_e="set +e"
> +  fi
> +  set +e
> +
> +  local duration
> +  local first_run=true
> +  local ret=1
> +  for duration in 0.01 0.1 0.3 1.0 2.0; do
> +    rm -f "${perfdata}" "${perfdata}".old
> +    perf record "$@" -o "${perfdata}" ${testprog_base} ${duration} > "$logfile" 2>&1

[Severity: Critical]
Does this predictable file path and unsafe shell redirection allow for an
arbitrary file overwrite via a symlink attack?

Since "perf test" is frequently run as root to evaluate system-wide profiling,
a local attacker could pre-create a symbolic link matching the
"/tmp/__perf_record_retry.$(id -u).$BASHPID.log" pattern to target arbitrary
system files.

The redirection here will follow the symlink without O_EXCL and overwrite the
target file with the output of the command. Could this be fixed by using mktemp
to securely create the temporary file?

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Sashiko AI review · https://sashiko.dev/#/patchset/20260616012744.4049193-1-irogers@google.com?part=5