diff options
| author | Abdelkader Boudih <freebsd@seuros.com> | 2026-06-17 14:49:52 +0000 |
|---|---|---|
| committer | Adrian Chadd <adrian@FreeBSD.org> | 2026-06-17 14:49:52 +0000 |
| commit | 021a190c88fc41f981a79fe6822bdafbcda14e99 (patch) | |
| tree | c02b3c162a56e2eac1e2d403403126d29f0d2dca | |
| parent | f981fa12b760a5f0983eeec8065a4dec5295ab24 (diff) | |
est: prevent divide-by-zero in est_msr_info
When hw.est.msr_info=1 is set, est_msr_info() extracts the bus clock
from MSR_PERF_STATUS upper bits. On secondary CPUs, the MSR may
contain zero in the frequency ratio field, causing a
divide-by-zero panic.
Observed in pre Skylake Intel cpu.
Reviewed by: adrian
Differential Revision: https://reviews.freebsd.org/D57614
| -rw-r--r-- | sys/x86/cpufreq/est.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/sys/x86/cpufreq/est.c b/sys/x86/cpufreq/est.c index 82f35934aa99..804de162ec60 100644 --- a/sys/x86/cpufreq/est.c +++ b/sys/x86/cpufreq/est.c @@ -1181,11 +1181,15 @@ est_msr_info(device_t dev, uint64_t msr, freq_info **freqs, size_t *freqslen) /* Figure out the bus clock. */ freq = atomic_load_acq_64(&tsc_freq) / 1000000; id = msr >> 32; + if ((id >> 8) == 0) + return (EOPNOTSUPP); bus = freq / (id >> 8); device_printf(dev, "Guessed bus clock (high) of %d MHz\n", bus); if (!bus_speed_ok(bus)) { /* We may be running on the low frequency. */ id = msr >> 48; + if ((id >> 8) == 0) + return (EOPNOTSUPP); bus = freq / (id >> 8); device_printf(dev, "Guessed bus clock (low) of %d MHz\n", bus); if (!bus_speed_ok(bus)) |