Re: [PATCH v5 2/8] s390/sclp: rework sclp boundary checks
On 9/11/20 6:24 AM, Cornelia Huck wrote:
> On Thu, 10 Sep 2020 19:45:01 +0200
> Thomas Huth wrote:
>
>> On 10/09/2020 11.36, Collin Walling wrote:
>>> Rework the SCLP boundary check to account for different SCLP commands
>>> (eventually) allowing different boundary sizes.
>>>
>>> Signed-off-by: Collin Walling
>>> Acked-by: Janosch Frank
>>> Reviewed-by: Cornelia Huck
>>> ---
>>> hw/s390x/sclp.c | 19 ++-
>>> 1 file changed, 18 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/hw/s390x/sclp.c b/hw/s390x/sclp.c
>>> index 28b973de8f..69a8724dc7 100644
>>> --- a/hw/s390x/sclp.c
>>> +++ b/hw/s390x/sclp.c
>>> @@ -49,6 +49,18 @@ static inline bool sclp_command_code_valid(uint32_t code)
>>> return false;
>>> }
>>>
>>> +static bool sccb_verify_boundary(uint64_t sccb_addr, uint16_t len)
>>
>> Maybe it would be good to add a comment in front of the function to say
>> that len must be big endian?
>
> What about renaming it to sccb_h_len or so? That would make it more
> clear that the parameter is not just some random length.
>
I think that makes sense.
>>
>> Thomas
>>
>>> +{
>>> +uint64_t sccb_max_addr = sccb_addr + be16_to_cpu(len) - 1;
>>> +uint64_t sccb_boundary = (sccb_addr & PAGE_MASK) + PAGE_SIZE;
>>> +
>>> +if (sccb_max_addr < sccb_boundary) {
>>> +return true;
>>> +}
>>> +
>>> +return false;
>>> +}
>>> +
>>> static void prepare_cpu_entries(MachineState *ms, CPUEntry *entry, int
>>> *count)
>>> {
>>> uint8_t features[SCCB_CPU_FEATURE_LEN] = { 0 };
>>> @@ -229,6 +241,11 @@ int sclp_service_call_protected(CPUS390XState *env,
>>> uint64_t sccb,
>>> goto out_write;
>>> }
>>>
>>> +if (!sccb_verify_boundary(sccb, work_sccb.h.length)) {
>
> ...name inspired by the 'h' in here.
>
>>> +work_sccb.h.response_code =
>>> cpu_to_be16(SCLP_RC_SCCB_BOUNDARY_VIOLATION);
>>> +goto out_write;
>>> +}
>>> +
>>> sclp_c->execute(sclp, _sccb, code);
>>> out_write:
>>> s390_cpu_pv_mem_write(env_archcpu(env), 0, _sccb,
>>> @@ -274,7 +291,7 @@ int sclp_service_call(CPUS390XState *env, uint64_t
>>> sccb, uint32_t code)
>>> goto out_write;
>>> }
>>>
>>> -if ((sccb + be16_to_cpu(work_sccb.h.length)) > ((sccb & PAGE_MASK) +
>>> PAGE_SIZE)) {
>>> +if (!sccb_verify_boundary(sccb, work_sccb.h.length)) {
>>> work_sccb.h.response_code =
>>> cpu_to_be16(SCLP_RC_SCCB_BOUNDARY_VIOLATION);
>>> goto out_write;
>>> }
>>>
>>
>
>
--
Regards,
Collin
Stay safe and stay healthy
Re: [PATCH v5 2/8] s390/sclp: rework sclp boundary checks
On Thu, 10 Sep 2020 19:45:01 +0200
Thomas Huth wrote:
> On 10/09/2020 11.36, Collin Walling wrote:
> > Rework the SCLP boundary check to account for different SCLP commands
> > (eventually) allowing different boundary sizes.
> >
> > Signed-off-by: Collin Walling
> > Acked-by: Janosch Frank
> > Reviewed-by: Cornelia Huck
> > ---
> > hw/s390x/sclp.c | 19 ++-
> > 1 file changed, 18 insertions(+), 1 deletion(-)
> >
> > diff --git a/hw/s390x/sclp.c b/hw/s390x/sclp.c
> > index 28b973de8f..69a8724dc7 100644
> > --- a/hw/s390x/sclp.c
> > +++ b/hw/s390x/sclp.c
> > @@ -49,6 +49,18 @@ static inline bool sclp_command_code_valid(uint32_t code)
> > return false;
> > }
> >
> > +static bool sccb_verify_boundary(uint64_t sccb_addr, uint16_t len)
>
> Maybe it would be good to add a comment in front of the function to say
> that len must be big endian?
What about renaming it to sccb_h_len or so? That would make it more
clear that the parameter is not just some random length.
>
> Thomas
>
> > +{
> > +uint64_t sccb_max_addr = sccb_addr + be16_to_cpu(len) - 1;
> > +uint64_t sccb_boundary = (sccb_addr & PAGE_MASK) + PAGE_SIZE;
> > +
> > +if (sccb_max_addr < sccb_boundary) {
> > +return true;
> > +}
> > +
> > +return false;
> > +}
> > +
> > static void prepare_cpu_entries(MachineState *ms, CPUEntry *entry, int
> > *count)
> > {
> > uint8_t features[SCCB_CPU_FEATURE_LEN] = { 0 };
> > @@ -229,6 +241,11 @@ int sclp_service_call_protected(CPUS390XState *env,
> > uint64_t sccb,
> > goto out_write;
> > }
> >
> > +if (!sccb_verify_boundary(sccb, work_sccb.h.length)) {
...name inspired by the 'h' in here.
> > +work_sccb.h.response_code =
> > cpu_to_be16(SCLP_RC_SCCB_BOUNDARY_VIOLATION);
> > +goto out_write;
> > +}
> > +
> > sclp_c->execute(sclp, _sccb, code);
> > out_write:
> > s390_cpu_pv_mem_write(env_archcpu(env), 0, _sccb,
> > @@ -274,7 +291,7 @@ int sclp_service_call(CPUS390XState *env, uint64_t
> > sccb, uint32_t code)
> > goto out_write;
> > }
> >
> > -if ((sccb + be16_to_cpu(work_sccb.h.length)) > ((sccb & PAGE_MASK) +
> > PAGE_SIZE)) {
> > +if (!sccb_verify_boundary(sccb, work_sccb.h.length)) {
> > work_sccb.h.response_code =
> > cpu_to_be16(SCLP_RC_SCCB_BOUNDARY_VIOLATION);
> > goto out_write;
> > }
> >
>
Re: [PATCH v5 2/8] s390/sclp: rework sclp boundary checks
On 10/09/2020 11.36, Collin Walling wrote:
> Rework the SCLP boundary check to account for different SCLP commands
> (eventually) allowing different boundary sizes.
>
> Signed-off-by: Collin Walling
> Acked-by: Janosch Frank
> Reviewed-by: Cornelia Huck
> ---
> hw/s390x/sclp.c | 19 ++-
> 1 file changed, 18 insertions(+), 1 deletion(-)
>
> diff --git a/hw/s390x/sclp.c b/hw/s390x/sclp.c
> index 28b973de8f..69a8724dc7 100644
> --- a/hw/s390x/sclp.c
> +++ b/hw/s390x/sclp.c
> @@ -49,6 +49,18 @@ static inline bool sclp_command_code_valid(uint32_t code)
> return false;
> }
>
> +static bool sccb_verify_boundary(uint64_t sccb_addr, uint16_t len)
Maybe it would be good to add a comment in front of the function to say
that len must be big endian?
Thomas
> +{
> +uint64_t sccb_max_addr = sccb_addr + be16_to_cpu(len) - 1;
> +uint64_t sccb_boundary = (sccb_addr & PAGE_MASK) + PAGE_SIZE;
> +
> +if (sccb_max_addr < sccb_boundary) {
> +return true;
> +}
> +
> +return false;
> +}
> +
> static void prepare_cpu_entries(MachineState *ms, CPUEntry *entry, int
> *count)
> {
> uint8_t features[SCCB_CPU_FEATURE_LEN] = { 0 };
> @@ -229,6 +241,11 @@ int sclp_service_call_protected(CPUS390XState *env,
> uint64_t sccb,
> goto out_write;
> }
>
> +if (!sccb_verify_boundary(sccb, work_sccb.h.length)) {
> +work_sccb.h.response_code =
> cpu_to_be16(SCLP_RC_SCCB_BOUNDARY_VIOLATION);
> +goto out_write;
> +}
> +
> sclp_c->execute(sclp, _sccb, code);
> out_write:
> s390_cpu_pv_mem_write(env_archcpu(env), 0, _sccb,
> @@ -274,7 +291,7 @@ int sclp_service_call(CPUS390XState *env, uint64_t sccb,
> uint32_t code)
> goto out_write;
> }
>
> -if ((sccb + be16_to_cpu(work_sccb.h.length)) > ((sccb & PAGE_MASK) +
> PAGE_SIZE)) {
> +if (!sccb_verify_boundary(sccb, work_sccb.h.length)) {
> work_sccb.h.response_code =
> cpu_to_be16(SCLP_RC_SCCB_BOUNDARY_VIOLATION);
> goto out_write;
> }
>
