| Message ID | 1464203363-20599-1-git-send-email-hotran@apm.com (mailing list archive) |
|---|---|
| State | Accepted, archived |
| Delegated to: | Rafael Wysocki |
| Headers | show |
On 25 May 2016 at 15:09, Hoan Tran <hotran@apm.com> wrote: > When CPPC fails to request PCC channel, the CPC data is freed > and cpc_desc_ptr points to the invalid data. This change prevents > this issue by moving cpc_desc_ptr assignment after PCC channel > request. > > Signed-off-by: Hoan Tran <hotran@apm.com> > --- > drivers/acpi/cppc_acpi.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c > index 8adac69..85fd8f7 100644 > --- a/drivers/acpi/cppc_acpi.c > +++ b/drivers/acpi/cppc_acpi.c > @@ -595,9 +595,6 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr) > /* Store CPU Logical ID */ > cpc_ptr->cpu_id = pr->id; > > - /* Plug it into this CPUs CPC descriptor. */ > - per_cpu(cpc_desc_ptr, pr->id) = cpc_ptr; > - > /* Parse PSD data for this CPU */ > ret = acpi_get_psd(cpc_ptr, handle); > if (ret) > @@ -610,6 +607,9 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr) > goto out_free; > } > > + /* Plug PSD data into this CPUs CPC descriptor. */ > + per_cpu(cpc_desc_ptr, pr->id) = cpc_ptr; > + Are you seeing a real problem without this change? I'm missing where this pointer is dereferenced if the PCC channel request fails. Thanks, Ashwin. -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Ashwin, Yes, I saw kernel crash. As cpc_desc_ptr is not NULL, cppc_cpufreq_init() still can pass then crash during cppc_get_perf_caps() access CPPC shared memory. It's not only "PCC channel request fail" can create this issue but "acpi_get_psd() fail" also creates it Thanks Hoan On Fri, May 27, 2016 at 9:10 AM, Ashwin Chaugule <ashwin.chaugule@linaro.org> wrote: > On 25 May 2016 at 15:09, Hoan Tran <hotran@apm.com> wrote: >> When CPPC fails to request PCC channel, the CPC data is freed >> and cpc_desc_ptr points to the invalid data. This change prevents >> this issue by moving cpc_desc_ptr assignment after PCC channel >> request. >> >> Signed-off-by: Hoan Tran <hotran@apm.com> >> --- >> drivers/acpi/cppc_acpi.c | 6 +++--- >> 1 file changed, 3 insertions(+), 3 deletions(-) >> >> diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c >> index 8adac69..85fd8f7 100644 >> --- a/drivers/acpi/cppc_acpi.c >> +++ b/drivers/acpi/cppc_acpi.c >> @@ -595,9 +595,6 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr) >> /* Store CPU Logical ID */ >> cpc_ptr->cpu_id = pr->id; >> >> - /* Plug it into this CPUs CPC descriptor. */ >> - per_cpu(cpc_desc_ptr, pr->id) = cpc_ptr; >> - >> /* Parse PSD data for this CPU */ >> ret = acpi_get_psd(cpc_ptr, handle); >> if (ret) >> @@ -610,6 +607,9 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr) >> goto out_free; >> } >> >> + /* Plug PSD data into this CPUs CPC descriptor. */ >> + per_cpu(cpc_desc_ptr, pr->id) = cpc_ptr; >> + > > Are you seeing a real problem without this change? I'm missing where > this pointer is dereferenced if the PCC channel request fails. > > Thanks, > Ashwin. -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 27 May 2016 at 12:41, Hoan Tran <hotran@apm.com> wrote: > Hi Ashwin, Hi, > > Yes, I saw kernel crash. > As cpc_desc_ptr is not NULL, cppc_cpufreq_init() still can pass then > crash during cppc_get_perf_caps() access CPPC shared memory. > > It's not only "PCC channel request fail" can create this issue but > "acpi_get_psd() fail" also creates it > > Thanks > Hoan Just for future reference. :) https://web.archive.org/web/20080722025748/http://www.zip.com.au/~akpm/linux/patches/stuff/top-posting.txt > > On Fri, May 27, 2016 at 9:10 AM, Ashwin Chaugule > <ashwin.chaugule@linaro.org> wrote: >> On 25 May 2016 at 15:09, Hoan Tran <hotran@apm.com> wrote: >>> When CPPC fails to request PCC channel, the CPC data is freed >>> and cpc_desc_ptr points to the invalid data. This change prevents >>> this issue by moving cpc_desc_ptr assignment after PCC channel >>> request. >>> >>> Signed-off-by: Hoan Tran <hotran@apm.com> >>> --- >>> drivers/acpi/cppc_acpi.c | 6 +++--- >>> 1 file changed, 3 insertions(+), 3 deletions(-) >>> >>> diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c >>> index 8adac69..85fd8f7 100644 >>> --- a/drivers/acpi/cppc_acpi.c >>> +++ b/drivers/acpi/cppc_acpi.c >>> @@ -595,9 +595,6 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr) >>> /* Store CPU Logical ID */ >>> cpc_ptr->cpu_id = pr->id; >>> >>> - /* Plug it into this CPUs CPC descriptor. */ >>> - per_cpu(cpc_desc_ptr, pr->id) = cpc_ptr; >>> - >>> /* Parse PSD data for this CPU */ >>> ret = acpi_get_psd(cpc_ptr, handle); >>> if (ret) >>> @@ -610,6 +607,9 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr) >>> goto out_free; >>> } >>> >>> + /* Plug PSD data into this CPUs CPC descriptor. */ >>> + per_cpu(cpc_desc_ptr, pr->id) = cpc_ptr; >>> + >> >> Are you seeing a real problem without this change? I'm missing where >> this pointer is dereferenced if the PCC channel request fails. >> So, after freeing the cpc_ptr, we need to NULL the per-cpu pointer as well. Alternately, not assign it until everything passes and rely on the static declaration, which is the path you've taken here. Acked-by: Ashwin Chaugule <ashwin.chaugule@linaro.org> -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Ashwin, On Tue, May 31, 2016 at 12:29 PM, Ashwin Chaugule <ashwin.chaugule@linaro.org> wrote: > On 27 May 2016 at 12:41, Hoan Tran <hotran@apm.com> wrote: >> Hi Ashwin, > > Hi, > >> >> Yes, I saw kernel crash. >> As cpc_desc_ptr is not NULL, cppc_cpufreq_init() still can pass then >> crash during cppc_get_perf_caps() access CPPC shared memory. >> >> It's not only "PCC channel request fail" can create this issue but >> "acpi_get_psd() fail" also creates it >> >> Thanks >> Hoan > > > Just for future reference. :) > > https://web.archive.org/web/20080722025748/http://www.zip.com.au/~akpm/linux/patches/stuff/top-posting.txt My mistake and will fix in future :) > > >> >> On Fri, May 27, 2016 at 9:10 AM, Ashwin Chaugule >> <ashwin.chaugule@linaro.org> wrote: >>> On 25 May 2016 at 15:09, Hoan Tran <hotran@apm.com> wrote: >>>> When CPPC fails to request PCC channel, the CPC data is freed >>>> and cpc_desc_ptr points to the invalid data. This change prevents >>>> this issue by moving cpc_desc_ptr assignment after PCC channel >>>> request. >>>> >>>> Signed-off-by: Hoan Tran <hotran@apm.com> >>>> --- >>>> drivers/acpi/cppc_acpi.c | 6 +++--- >>>> 1 file changed, 3 insertions(+), 3 deletions(-) >>>> >>>> diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c >>>> index 8adac69..85fd8f7 100644 >>>> --- a/drivers/acpi/cppc_acpi.c >>>> +++ b/drivers/acpi/cppc_acpi.c >>>> @@ -595,9 +595,6 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr) >>>> /* Store CPU Logical ID */ >>>> cpc_ptr->cpu_id = pr->id; >>>> >>>> - /* Plug it into this CPUs CPC descriptor. */ >>>> - per_cpu(cpc_desc_ptr, pr->id) = cpc_ptr; >>>> - >>>> /* Parse PSD data for this CPU */ >>>> ret = acpi_get_psd(cpc_ptr, handle); >>>> if (ret) >>>> @@ -610,6 +607,9 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr) >>>> goto out_free; >>>> } >>>> >>>> + /* Plug PSD data into this CPUs CPC descriptor. */ >>>> + per_cpu(cpc_desc_ptr, pr->id) = cpc_ptr; >>>> + >>> >>> Are you seeing a real problem without this change? I'm missing where >>> this pointer is dereferenced if the PCC channel request fails. >>> > > So, after freeing the cpc_ptr, we need to NULL the per-cpu pointer as > well. Alternately, not assign it until everything passes and rely on > the static declaration, which is the path you've taken here. > > Acked-by: Ashwin Chaugule <ashwin.chaugule@linaro.org> Thanks Hoan -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, May 31, 2016 at 12:29 PM, Ashwin Chaugule <ashwin.chaugule@linaro.org> wrote: > > On 27 May 2016 at 12:41, Hoan Tran <hotran@apm.com> wrote: > > Hi Ashwin, > > Hi, > > > > > Yes, I saw kernel crash. > > As cpc_desc_ptr is not NULL, cppc_cpufreq_init() still can pass then > > crash during cppc_get_perf_caps() access CPPC shared memory. > > > > It's not only "PCC channel request fail" can create this issue but > > "acpi_get_psd() fail" also creates it > > > > Thanks > > Hoan > > > Just for future reference. :) > > https://web.archive.org/web/20080722025748/http://www.zip.com.au/~akpm/linux/patches/stuff/top-posting.txt > > > > > > On Fri, May 27, 2016 at 9:10 AM, Ashwin Chaugule > > <ashwin.chaugule@linaro.org> wrote: > >> On 25 May 2016 at 15:09, Hoan Tran <hotran@apm.com> wrote: > >>> When CPPC fails to request PCC channel, the CPC data is freed > >>> and cpc_desc_ptr points to the invalid data. This change prevents > >>> this issue by moving cpc_desc_ptr assignment after PCC channel > >>> request. > >>> > >>> Signed-off-by: Hoan Tran <hotran@apm.com> > >>> --- > >>> drivers/acpi/cppc_acpi.c | 6 +++--- > >>> 1 file changed, 3 insertions(+), 3 deletions(-) > >>> > >>> diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c > >>> index 8adac69..85fd8f7 100644 > >>> --- a/drivers/acpi/cppc_acpi.c > >>> +++ b/drivers/acpi/cppc_acpi.c > >>> @@ -595,9 +595,6 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr) > >>> /* Store CPU Logical ID */ > >>> cpc_ptr->cpu_id = pr->id; > >>> > >>> - /* Plug it into this CPUs CPC descriptor. */ > >>> - per_cpu(cpc_desc_ptr, pr->id) = cpc_ptr; > >>> - > >>> /* Parse PSD data for this CPU */ > >>> ret = acpi_get_psd(cpc_ptr, handle); > >>> if (ret) > >>> @@ -610,6 +607,9 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr) > >>> goto out_free; > >>> } > >>> > >>> + /* Plug PSD data into this CPUs CPC descriptor. */ > >>> + per_cpu(cpc_desc_ptr, pr->id) = cpc_ptr; > >>> + > >> > >> Are you seeing a real problem without this change? I'm missing where > >> this pointer is dereferenced if the PCC channel request fails. > >> > > So, after freeing the cpc_ptr, we need to NULL the per-cpu pointer as > well. Alternately, not assign it until everything passes and rely on > the static declaration, which is the path you've taken here. > > Acked-by: Ashwin Chaugule <ashwin.chaugule@linaro.org> Hi Rafael, Do you have plan to apply this patch ? Thanks Hoan -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Friday, June 24, 2016 09:35:32 AM Hoan Tran wrote: > On Tue, May 31, 2016 at 12:29 PM, Ashwin Chaugule > <ashwin.chaugule@linaro.org> wrote: > > > > On 27 May 2016 at 12:41, Hoan Tran <hotran@apm.com> wrote: > > > Hi Ashwin, > > > > Hi, > > > > > > > > Yes, I saw kernel crash. > > > As cpc_desc_ptr is not NULL, cppc_cpufreq_init() still can pass then > > > crash during cppc_get_perf_caps() access CPPC shared memory. > > > > > > It's not only "PCC channel request fail" can create this issue but > > > "acpi_get_psd() fail" also creates it > > > > > > Thanks > > > Hoan > > > > > > Just for future reference. :) > > > > https://web.archive.org/web/20080722025748/http://www.zip.com.au/~akpm/linux/patches/stuff/top-posting.txt > > > > > > > > > > On Fri, May 27, 2016 at 9:10 AM, Ashwin Chaugule > > > <ashwin.chaugule@linaro.org> wrote: > > >> On 25 May 2016 at 15:09, Hoan Tran <hotran@apm.com> wrote: > > >>> When CPPC fails to request PCC channel, the CPC data is freed > > >>> and cpc_desc_ptr points to the invalid data. This change prevents > > >>> this issue by moving cpc_desc_ptr assignment after PCC channel > > >>> request. > > >>> > > >>> Signed-off-by: Hoan Tran <hotran@apm.com> > > >>> --- > > >>> drivers/acpi/cppc_acpi.c | 6 +++--- > > >>> 1 file changed, 3 insertions(+), 3 deletions(-) > > >>> > > >>> diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c > > >>> index 8adac69..85fd8f7 100644 > > >>> --- a/drivers/acpi/cppc_acpi.c > > >>> +++ b/drivers/acpi/cppc_acpi.c > > >>> @@ -595,9 +595,6 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr) > > >>> /* Store CPU Logical ID */ > > >>> cpc_ptr->cpu_id = pr->id; > > >>> > > >>> - /* Plug it into this CPUs CPC descriptor. */ > > >>> - per_cpu(cpc_desc_ptr, pr->id) = cpc_ptr; > > >>> - > > >>> /* Parse PSD data for this CPU */ > > >>> ret = acpi_get_psd(cpc_ptr, handle); > > >>> if (ret) > > >>> @@ -610,6 +607,9 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr) > > >>> goto out_free; > > >>> } > > >>> > > >>> + /* Plug PSD data into this CPUs CPC descriptor. */ > > >>> + per_cpu(cpc_desc_ptr, pr->id) = cpc_ptr; > > >>> + > > >> > > >> Are you seeing a real problem without this change? I'm missing where > > >> this pointer is dereferenced if the PCC channel request fails. > > >> > > > > So, after freeing the cpc_ptr, we need to NULL the per-cpu pointer as > > well. Alternately, not assign it until everything passes and rely on > > the static declaration, which is the path you've taken here. > > > > Acked-by: Ashwin Chaugule <ashwin.chaugule@linaro.org> > > Hi Rafael, > > Do you have plan to apply this patch ? I do now. :-) I've overlooked the Ashwin's ACK, so thanks for the reminder. Thanks, Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c index 8adac69..85fd8f7 100644 --- a/drivers/acpi/cppc_acpi.c +++ b/drivers/acpi/cppc_acpi.c @@ -595,9 +595,6 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr) /* Store CPU Logical ID */ cpc_ptr->cpu_id = pr->id; - /* Plug it into this CPUs CPC descriptor. */ - per_cpu(cpc_desc_ptr, pr->id) = cpc_ptr; - /* Parse PSD data for this CPU */ ret = acpi_get_psd(cpc_ptr, handle); if (ret) @@ -610,6 +607,9 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr) goto out_free; } + /* Plug PSD data into this CPUs CPC descriptor. */ + per_cpu(cpc_desc_ptr, pr->id) = cpc_ptr; + /* Everything looks okay */ pr_debug("Parsed CPC struct for CPU: %d\n", pr->id);
When CPPC fails to request PCC channel, the CPC data is freed and cpc_desc_ptr points to the invalid data. This change prevents this issue by moving cpc_desc_ptr assignment after PCC channel request. Signed-off-by: Hoan Tran <hotran@apm.com> --- drivers/acpi/cppc_acpi.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)