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| author | Samuel Moelius <sam.moelius@trailofbits.com> | 2026-06-29 15:26:17 +0000 |
|---|---|---|
| committer | Steven Rostedt <rostedt@goodmis.org> | 2026-07-28 07:18:50 -0400 |
| commit | ac00ffdbbc832f4c8ad5312217360d542f7e6690 (patch) | |
| tree | 5ecca310b72c28b405054543b02cec94782b6df1 /samples/ftrace | |
| parent | 693dc27c5286cb0fd0d8cf18c3ee924b22154e92 (diff) | |
| download | lwn-ac00ffdbbc832f4c8ad5312217360d542f7e6690.tar.gz lwn-ac00ffdbbc832f4c8ad5312217360d542f7e6690.zip | |
samples/ftrace: Prevent division by zero when nr_function_calls is zero
The ftrace-ops sample exposes nr_function_calls as a module parameter
and uses it as the divisor when printing the measured time per call.
Loading the module with nr_function_calls=0 skips the benchmark loop and
then divides the elapsed time by zero, crashing the kernel during sample
module initialization.
Keep accepting the parameter value, but report -1LL as the per-call
duration when the call count is zero instead of dividing by it.
Link: https://patch.msgid.link/20260629152616.107080.e19bfbed249c.ftrace-ops-zero-function-calls-div0@trailofbits.com
Assisted-by: Codex:gpt-5.5-cyber-preview
Signed-off-by: Samuel Moelius <sam.moelius@trailofbits.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'samples/ftrace')
| -rw-r--r-- | samples/ftrace/ftrace-ops.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/samples/ftrace/ftrace-ops.c b/samples/ftrace/ftrace-ops.c index 152ffc1a30b6..8cae38d8b879 100644 --- a/samples/ftrace/ftrace-ops.c +++ b/samples/ftrace/ftrace-ops.c @@ -223,7 +223,7 @@ static int __init ftrace_ops_sample_init(void) pr_info("Attempted %u calls to %ps in %lluns (%lluns / call)\n", nr_function_calls, tracee_relevant, - period, div_u64(period, nr_function_calls)); + period, nr_function_calls ? div_u64(period, nr_function_calls) : -1LL); if (persist) return 0; |