cpufreq: stats: Fix potential out-of-bounds access in deferred reset

cpufreq_stats_create_table() sets stats->last_index to -1 if policy->cur
is not in the frequency table. It then stays at -1, because
cpufreq_stats_record_transition() returns early on old_index == -1 before
it gets to update last_index.

Commit 46a310b80bc2 ("[CPUFREQ] Don't set stat->last_index to -1 if
the pol->cur has incorrect value.") added that check. However, since
commit 40c3bd4cfa6f ("cpufreq: stats: Defer stats update to
cpufreq_stats_record_transition()"), the stats reset is deferred to the
beginning of cpufreq_stats_record_transition(), before that check, and
cpufreq_stats_reset_table() ends with an unconditional
cpufreq_stats_update(). So if the "reset" attribute is written while
last_index is -1, the next frequency transition accesses
time_in_state[-1].

Fix it by also returning early on last_index == -1 in
cpufreq_stats_reset_table().

Fixes: 40c3bd4cfa6f ("cpufreq: stats: Defer stats update to cpufreq_stats_record_transition()")
Cc: 5.10+ <stable@vger.kernel.org> # 5.10+
Signed-off-by: Zhongqiu Han <zhongqiu.han@oss.qualcomm.com>
Link: https://patch.msgid.link/20261027133332.377546-1-zhongqiu.han@oss.qualcomm.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

0 files changed, 0 insertions, 0 deletions