Messages in this thread | | | Date | Thu, 9 Feb 2023 13:03:52 +0800 | From | Huang Rui <> | Subject | Re: [PATCH] cpufreq: amd-pstate: avoid uninitialized variable use |
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On Wed, Feb 08, 2023 at 12:12:51AM +0800, Arnd Bergmann wrote: > From: Arnd Bergmann <arnd@arndb.de> > > The new epp support causes warnings about three separate > but related bugs: > > 1) failing before allocation should just return an error: > > drivers/cpufreq/amd-pstate.c:951:6: error: variable 'ret' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized] > if (!dev) > ^~~~ > drivers/cpufreq/amd-pstate.c:1018:9: note: uninitialized use occurs here > return ret; > ^~~ > > 2) wrong variable to store return code: > > drivers/cpufreq/amd-pstate.c:963:6: error: variable 'ret' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized] > if (rc) > ^~ > drivers/cpufreq/amd-pstate.c:1019:9: note: uninitialized use occurs here > return ret; > ^~~ > drivers/cpufreq/amd-pstate.c:963:2: note: remove the 'if' if its condition is always false > if (rc) > ^~~~~~~ > > 3) calling amd_pstate_set_epp() in cleanup path after determining > that it should not be called: > > drivers/cpufreq/amd-pstate.c:1055:6: error: variable 'epp' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized] > if (cpudata->epp_policy == cpudata->policy) > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > drivers/cpufreq/amd-pstate.c:1080:30: note: uninitialized use occurs here > amd_pstate_set_epp(cpudata, epp); > ^~~ > > All three are trivial to fix, but most likely there are additional bugs > in this function when the error handling was not really tested. > > Fixes: ffa5096a7c33 ("cpufreq: amd-pstate: implement Pstate EPP support for the AMD processors") > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Thanks!
Acked-by: Huang Rui <ray.huang@amd.com>
> --- > drivers/cpufreq/amd-pstate.c | 9 ++++----- > 1 file changed, 4 insertions(+), 5 deletions(-) > > diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c > index 168a28bed6ee..847f5f31396d 100644 > --- a/drivers/cpufreq/amd-pstate.c > +++ b/drivers/cpufreq/amd-pstate.c > @@ -940,7 +940,6 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy) > int min_freq, max_freq, nominal_freq, lowest_nonlinear_freq, ret; > struct amd_cpudata *cpudata; > struct device *dev; > - int rc; > u64 value; > > /* > @@ -950,7 +949,7 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy) > amd_perf_ctl_reset(policy->cpu); > dev = get_cpu_device(policy->cpu); > if (!dev) > - goto free_cpudata1; > + return -ENODEV; > > cpudata = kzalloc(sizeof(*cpudata), GFP_KERNEL); > if (!cpudata) > @@ -959,8 +958,8 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy) > cpudata->cpu = policy->cpu; > cpudata->epp_policy = 0; > > - rc = amd_pstate_init_perf(cpudata); > - if (rc) > + ret = amd_pstate_init_perf(cpudata); > + if (ret) > goto free_cpudata1; > > min_freq = amd_get_min_freq(cpudata); > @@ -1076,9 +1075,9 @@ static void amd_pstate_epp_init(unsigned int cpu) > value |= (u64)epp << 24; > } > > + amd_pstate_set_epp(cpudata, epp); > skip_epp: > WRITE_ONCE(cpudata->cppc_req_cached, value); > - amd_pstate_set_epp(cpudata, epp); > cpufreq_cpu_put(policy); > } > > -- > 2.39.1 >
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