From: Thomas Renninger Date: Mon, 14 Dec 2009 10:44:15 +0000 (+0100) Subject: CPUFREQ: Fix use after free of struct powernow_k8_data X-Git-Tag: v2.6.31.13~82 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e8772825003228c6c5dd94af7238a1b1fc12ec68;p=thirdparty%2Fkernel%2Fstable.git CPUFREQ: Fix use after free of struct powernow_k8_data commit 557a701c16553b0b691dbb64ef30361115a80f64 upstream. Easy fix for a regression introduced in 2.6.31. On managed CPUs the cpufreq.c core will call driver->exit(cpu) on the managed cpus and powernow_k8 will free the core's data. Later driver->get(cpu) function might get called trying to read out the current freq of a managed cpu and the NULL pointer check does not work on the freed object -> better set it to NULL. ->get() is unsigned and must return 0 as invalid frequency. Reference: http://bugzilla.kernel.org/show_bug.cgi?id=14391 Signed-off-by: Thomas Renninger Tested-by: Michal Schmidt Signed-off-by: Dave Jones Signed-off-by: Greg Kroah-Hartman --- diff --git a/arch/x86/kernel/cpu/cpufreq/powernow-k8.c b/arch/x86/kernel/cpu/cpufreq/powernow-k8.c index fde0cd3b382ac..8cbfb42cbef2f 100644 --- a/arch/x86/kernel/cpu/cpufreq/powernow-k8.c +++ b/arch/x86/kernel/cpu/cpufreq/powernow-k8.c @@ -1372,6 +1372,7 @@ static int __devexit powernowk8_cpu_exit(struct cpufreq_policy *pol) kfree(data->powernow_table); kfree(data); + per_cpu(powernow_data, pol->cpu) = NULL; return 0; } @@ -1391,7 +1392,7 @@ static unsigned int powernowk8_get(unsigned int cpu) int err; if (!data) - return -EINVAL; + return 0; smp_call_function_single(cpu, query_values_on_cpu, &err, true); if (err)