[v2,13/24] drm/etnaviv: reject timeouts with tv_nsec >= NSEC_PER_SEC

Message ID 20191213205417.3871055-4-arnd@arndb.de
State Superseded
Headers show
Series
  • Untitled series #25686
Related show

Commit Message

Arnd Bergmann Dec. 13, 2019, 8:53 p.m.
Most kernel interfaces that take a timespec require normalized
representation with tv_nsec between 0 and NSEC_PER_SEC.

Passing values larger than 0x100000000ull further behaves differently
on 32-bit and 64-bit kernels, and can cause the latter to spend a long
time counting seconds in timespec64_sub()/set_normalized_timespec64().

Reject those large values at the user interface to enforce sane and
portable behavior.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>

---
 drivers/gpu/drm/etnaviv/etnaviv_drv.c | 9 +++++++++
 1 file changed, 9 insertions(+)

-- 
2.20.0

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Comments

Guido Günther Jan. 17, 2020, 3:47 p.m. | #1
Hi,
On Fri, Dec 13, 2019 at 09:53:41PM +0100, Arnd Bergmann wrote:
> Most kernel interfaces that take a timespec require normalized

> representation with tv_nsec between 0 and NSEC_PER_SEC.

> 

> Passing values larger than 0x100000000ull further behaves differently

> on 32-bit and 64-bit kernels, and can cause the latter to spend a long

> time counting seconds in timespec64_sub()/set_normalized_timespec64().

> 

> Reject those large values at the user interface to enforce sane and

> portable behavior.

> 

> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

> ---

>  drivers/gpu/drm/etnaviv/etnaviv_drv.c | 9 +++++++++

>  1 file changed, 9 insertions(+)

> 

> diff --git a/drivers/gpu/drm/etnaviv/etnaviv_drv.c b/drivers/gpu/drm/etnaviv/etnaviv_drv.c

> index 1f9c01be40d7..95d72dc00280 100644

> --- a/drivers/gpu/drm/etnaviv/etnaviv_drv.c

> +++ b/drivers/gpu/drm/etnaviv/etnaviv_drv.c

> @@ -297,6 +297,9 @@ static int etnaviv_ioctl_gem_cpu_prep(struct drm_device *dev, void *data,

>  	if (args->op & ~(ETNA_PREP_READ | ETNA_PREP_WRITE | ETNA_PREP_NOSYNC))

>  		return -EINVAL;

>  

> +	if (args->timeout.tv_nsec > NSEC_PER_SEC)

> +		return -EINVAL;

> +

>  	obj = drm_gem_object_lookup(file, args->handle);

>  	if (!obj)

>  		return -ENOENT;

> @@ -360,6 +363,9 @@ static int etnaviv_ioctl_wait_fence(struct drm_device *dev, void *data,

>  	if (args->flags & ~(ETNA_WAIT_NONBLOCK))

>  		return -EINVAL;

>  

> +	if (args->timeout.tv_nsec > NSEC_PER_SEC)

> +		return -EINVAL;

> +

>  	if (args->pipe >= ETNA_MAX_PIPES)

>  		return -EINVAL;

>  

> @@ -411,6 +417,9 @@ static int etnaviv_ioctl_gem_wait(struct drm_device *dev, void *data,

>  	if (args->flags & ~(ETNA_WAIT_NONBLOCK))

>  		return -EINVAL;

>  

> +	if (args->timeout.tv_nsec > NSEC_PER_SEC)

> +		return -EINVAL;

> +

>  	if (args->pipe >= ETNA_MAX_PIPES)

>  		return -EINVAL;

>


This breaks rendering here on arm64/gc7000 due to

ioctl(6, DRM_IOCTL_ETNAVIV_GEM_CPU_PREP or DRM_IOCTL_MSM_GEM_CPU_PREP, 0xfffff7888680) = -1 EINVAL (Invalid argument)
ioctl(6, DRM_IOCTL_ETNAVIV_GEM_CPU_FINI or DRM_IOCTL_QXL_CLIENTCAP, 0xfffff78885e0) = 0
ioctl(6, DRM_IOCTL_ETNAVIV_GEM_CPU_PREP or DRM_IOCTL_MSM_GEM_CPU_PREP, 0xfffff7888680) = -1 EINVAL (Invalid argument)
ioctl(6, DRM_IOCTL_ETNAVIV_GEM_CPU_FINI or DRM_IOCTL_QXL_CLIENTCAP, 0xfffff78885e0) = 0
ioctl(6, DRM_IOCTL_ETNAVIV_GEM_CPU_PREP or DRM_IOCTL_MSM_GEM_CPU_PREP, 0xfffff7888680) = -1 EINVAL (Invalid argument)
ioctl(6, DRM_IOCTL_ETNAVIV_GEM_CPU_FINI or DRM_IOCTL_QXL_CLIENTCAP, 0xfffff78885e0) = 0

This is due to

    get_abs_timeout(&req.timeout, 5000000000);

in etna_bo_cpu_prep which can exceed NSEC_PER_SEC.

Should i send a patch to revert that change since it breaks existing userspace?

Cheers,
 -- Guido

> -- 

> 2.20.0

> 

> _______________________________________________

> etnaviv mailing list

> etnaviv@lists.freedesktop.org

> https://lists.freedesktop.org/mailman/listinfo/etnaviv

> 

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Lucas Stach Jan. 20, 2020, 5:47 p.m. | #2
On Fr, 2020-01-17 at 16:47 +0100, Guido Günther wrote:
> Hi,
> On Fri, Dec 13, 2019 at 09:53:41PM +0100, Arnd Bergmann wrote:
> > Most kernel interfaces that take a timespec require normalized
> > representation with tv_nsec between 0 and NSEC_PER_SEC.
> > 
> > Passing values larger than 0x100000000ull further behaves differently
> > on 32-bit and 64-bit kernels, and can cause the latter to spend a long
> > time counting seconds in timespec64_sub()/set_normalized_timespec64().
> > 
> > Reject those large values at the user interface to enforce sane and
> > portable behavior.
> > 
> > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> > ---
> >  drivers/gpu/drm/etnaviv/etnaviv_drv.c | 9 +++++++++
> >  1 file changed, 9 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/etnaviv/etnaviv_drv.c b/drivers/gpu/drm/etnaviv/etnaviv_drv.c
> > index 1f9c01be40d7..95d72dc00280 100644
> > --- a/drivers/gpu/drm/etnaviv/etnaviv_drv.c
> > +++ b/drivers/gpu/drm/etnaviv/etnaviv_drv.c
> > @@ -297,6 +297,9 @@ static int etnaviv_ioctl_gem_cpu_prep(struct drm_device *dev, void *data,
> >  	if (args->op & ~(ETNA_PREP_READ | ETNA_PREP_WRITE | ETNA_PREP_NOSYNC))
> >  		return -EINVAL;
> >  
> > +	if (args->timeout.tv_nsec > NSEC_PER_SEC)
> > +		return -EINVAL;
> > +
> >  	obj = drm_gem_object_lookup(file, args->handle);
> >  	if (!obj)
> >  		return -ENOENT;
> > @@ -360,6 +363,9 @@ static int etnaviv_ioctl_wait_fence(struct drm_device *dev, void *data,
> >  	if (args->flags & ~(ETNA_WAIT_NONBLOCK))
> >  		return -EINVAL;
> >  
> > +	if (args->timeout.tv_nsec > NSEC_PER_SEC)
> > +		return -EINVAL;
> > +
> >  	if (args->pipe >= ETNA_MAX_PIPES)
> >  		return -EINVAL;
> >  
> > @@ -411,6 +417,9 @@ static int etnaviv_ioctl_gem_wait(struct drm_device *dev, void *data,
> >  	if (args->flags & ~(ETNA_WAIT_NONBLOCK))
> >  		return -EINVAL;
> >  
> > +	if (args->timeout.tv_nsec > NSEC_PER_SEC)
> > +		return -EINVAL;
> > +
> >  	if (args->pipe >= ETNA_MAX_PIPES)
> >  		return -EINVAL;
> > 
> 
> This breaks rendering here on arm64/gc7000 due to
> 
> ioctl(6, DRM_IOCTL_ETNAVIV_GEM_CPU_PREP or DRM_IOCTL_MSM_GEM_CPU_PREP, 0xfffff7888680) = -1 EINVAL (Invalid argument)
> ioctl(6, DRM_IOCTL_ETNAVIV_GEM_CPU_FINI or DRM_IOCTL_QXL_CLIENTCAP, 0xfffff78885e0) = 0
> ioctl(6, DRM_IOCTL_ETNAVIV_GEM_CPU_PREP or DRM_IOCTL_MSM_GEM_CPU_PREP, 0xfffff7888680) = -1 EINVAL (Invalid argument)
> ioctl(6, DRM_IOCTL_ETNAVIV_GEM_CPU_FINI or DRM_IOCTL_QXL_CLIENTCAP, 0xfffff78885e0) = 0
> ioctl(6, DRM_IOCTL_ETNAVIV_GEM_CPU_PREP or DRM_IOCTL_MSM_GEM_CPU_PREP, 0xfffff7888680) = -1 EINVAL (Invalid argument)
> ioctl(6, DRM_IOCTL_ETNAVIV_GEM_CPU_FINI or DRM_IOCTL_QXL_CLIENTCAP, 0xfffff78885e0) = 0
> 
> This is due to
> 
>     get_abs_timeout(&req.timeout, 5000000000);
> 
> in etna_bo_cpu_prep which can exceed NSEC_PER_SEC.
> 
> Should i send a patch to revert that change since it breaks existing userspace?

No need to revert. This patch has not been applied to the etnaviv tree
yet, I guess it's just in one of Arnds branches feeding into -next.

That part of userspace is pretty dumb, as it misses to renormalize
tv_nsec when it overflows the second boundary. So if what I see is
correct it should be enough to allow 2 * NSEC_PER_SEC, which should
both reject broken large timeout and keep existing userspace working.

Regards,
Lucas
Arnd Bergmann Jan. 20, 2020, 6:47 p.m. | #3
On Mon, Jan 20, 2020 at 6:48 PM Lucas Stach <l.stach@pengutronix.de> wrote:
> On Fr, 2020-01-17 at 16:47 +0100, Guido Günther wrote:
> >
> > This breaks rendering here on arm64/gc7000 due to
> >
> > ioctl(6, DRM_IOCTL_ETNAVIV_GEM_CPU_PREP or DRM_IOCTL_MSM_GEM_CPU_PREP, 0xfffff7888680) = -1 EINVAL (Invalid argument)
> > ioctl(6, DRM_IOCTL_ETNAVIV_GEM_CPU_FINI or DRM_IOCTL_QXL_CLIENTCAP, 0xfffff78885e0) = 0
> > ioctl(6, DRM_IOCTL_ETNAVIV_GEM_CPU_PREP or DRM_IOCTL_MSM_GEM_CPU_PREP, 0xfffff7888680) = -1 EINVAL (Invalid argument)
> > ioctl(6, DRM_IOCTL_ETNAVIV_GEM_CPU_FINI or DRM_IOCTL_QXL_CLIENTCAP, 0xfffff78885e0) = 0
> > ioctl(6, DRM_IOCTL_ETNAVIV_GEM_CPU_PREP or DRM_IOCTL_MSM_GEM_CPU_PREP, 0xfffff7888680) = -1 EINVAL (Invalid argument)
> > ioctl(6, DRM_IOCTL_ETNAVIV_GEM_CPU_FINI or DRM_IOCTL_QXL_CLIENTCAP, 0xfffff78885e0) = 0
> >
> > This is due to
> >
> >     get_abs_timeout(&req.timeout, 5000000000);
> >
> > in etna_bo_cpu_prep which can exceed NSEC_PER_SEC.
> >
> > Should i send a patch to revert that change since it breaks existing userspace?
>
> No need to revert. This patch has not been applied to the etnaviv tree
> yet, I guess it's just in one of Arnds branches feeding into -next.
>
> That part of userspace is pretty dumb, as it misses to renormalize
> tv_nsec when it overflows the second boundary. So if what I see is
> correct it should be enough to allow 2 * NSEC_PER_SEC, which should
> both reject broken large timeout and keep existing userspace working.

Ah, so it's never more than 2 billion nanoseconds in known user space?
I can definitely change my patch (actually add one on top) to allow that
and handle it as before, or alternatively accept any 64-bit nanosecond value
as arm64 already did, but make it less inefficient to handle.

       Arnd
Lucas Stach Jan. 21, 2020, 10:21 a.m. | #4
On Mo, 2020-01-20 at 19:47 +0100, Arnd Bergmann wrote:
> On Mon, Jan 20, 2020 at 6:48 PM Lucas Stach <l.stach@pengutronix.de> wrote:
> > On Fr, 2020-01-17 at 16:47 +0100, Guido Günther wrote:
> > > This breaks rendering here on arm64/gc7000 due to
> > > 
> > > ioctl(6, DRM_IOCTL_ETNAVIV_GEM_CPU_PREP or DRM_IOCTL_MSM_GEM_CPU_PREP, 0xfffff7888680) = -1 EINVAL (Invalid argument)
> > > ioctl(6, DRM_IOCTL_ETNAVIV_GEM_CPU_FINI or DRM_IOCTL_QXL_CLIENTCAP, 0xfffff78885e0) = 0
> > > ioctl(6, DRM_IOCTL_ETNAVIV_GEM_CPU_PREP or DRM_IOCTL_MSM_GEM_CPU_PREP, 0xfffff7888680) = -1 EINVAL (Invalid argument)
> > > ioctl(6, DRM_IOCTL_ETNAVIV_GEM_CPU_FINI or DRM_IOCTL_QXL_CLIENTCAP, 0xfffff78885e0) = 0
> > > ioctl(6, DRM_IOCTL_ETNAVIV_GEM_CPU_PREP or DRM_IOCTL_MSM_GEM_CPU_PREP, 0xfffff7888680) = -1 EINVAL (Invalid argument)
> > > ioctl(6, DRM_IOCTL_ETNAVIV_GEM_CPU_FINI or DRM_IOCTL_QXL_CLIENTCAP, 0xfffff78885e0) = 0
> > > 
> > > This is due to
> > > 
> > >     get_abs_timeout(&req.timeout, 5000000000);
> > > 
> > > in etna_bo_cpu_prep which can exceed NSEC_PER_SEC.
> > > 
> > > Should i send a patch to revert that change since it breaks existing userspace?
> > 
> > No need to revert. This patch has not been applied to the etnaviv tree
> > yet, I guess it's just in one of Arnds branches feeding into -next.
> > 
> > That part of userspace is pretty dumb, as it misses to renormalize
> > tv_nsec when it overflows the second boundary. So if what I see is
> > correct it should be enough to allow 2 * NSEC_PER_SEC, which should
> > both reject broken large timeout and keep existing userspace working.
> 
> Ah, so it's never more than 2 billion nanoseconds in known user space?
> I can definitely change my patch (actually add one on top) to allow that
> and handle it as before, or alternatively accept any 64-bit nanosecond value
> as arm64 already did, but make it less inefficient to handle.

So the broken userspace code looks like this:

static inline void get_abs_timeout(struct drm_etnaviv_timespec *tv, uint64_t ns)
{
        struct timespec t;
        uint32_t s = ns / 1000000000;
        clock_gettime(CLOCK_MONOTONIC, &t);
        tv->tv_sec = t.tv_sec + s;
        tv->tv_nsec = t.tv_nsec + ns - (s * 1000000000);
}

Which means it _tries_ to do the right thing by putting the billion
part into the tv_sec member and only the remaining ns part is added to
tv_nsec, but then it fails to propagate a tv_nsec overflow over
NSEC_PER_SEC into tv_sec.

Which means the tv_nsec should never be more than 2 * NSEC_PER_SEC in
known userspace. I would prefer if we could make the interface as
strict as possible (i.e. no arbitrary large numbers in tv_nsec), while
keeping this specific corner case working.

Regards,
Lucas
Arnd Bergmann Jan. 21, 2020, 11:46 a.m. | #5
On Tue, Jan 21, 2020 at 11:22 AM Lucas Stach <l.stach@pengutronix.de> wrote:
>
> On Mo, 2020-01-20 at 19:47 +0100, Arnd Bergmann wrote:
> > On Mon, Jan 20, 2020 at 6:48 PM Lucas Stach <l.stach@pengutronix.de> wrote:
> > > On Fr, 2020-01-17 at 16:47 +0100, Guido Günther wrote:
> > > > This breaks rendering here on arm64/gc7000 due to
> > > >
> > > > ioctl(6, DRM_IOCTL_ETNAVIV_GEM_CPU_PREP or DRM_IOCTL_MSM_GEM_CPU_PREP, 0xfffff7888680) = -1 EINVAL (Invalid argument)
> > > > ioctl(6, DRM_IOCTL_ETNAVIV_GEM_CPU_FINI or DRM_IOCTL_QXL_CLIENTCAP, 0xfffff78885e0) = 0
> > > > ioctl(6, DRM_IOCTL_ETNAVIV_GEM_CPU_PREP or DRM_IOCTL_MSM_GEM_CPU_PREP, 0xfffff7888680) = -1 EINVAL (Invalid argument)
> > > > ioctl(6, DRM_IOCTL_ETNAVIV_GEM_CPU_FINI or DRM_IOCTL_QXL_CLIENTCAP, 0xfffff78885e0) = 0
> > > > ioctl(6, DRM_IOCTL_ETNAVIV_GEM_CPU_PREP or DRM_IOCTL_MSM_GEM_CPU_PREP, 0xfffff7888680) = -1 EINVAL (Invalid argument)
> > > > ioctl(6, DRM_IOCTL_ETNAVIV_GEM_CPU_FINI or DRM_IOCTL_QXL_CLIENTCAP, 0xfffff78885e0) = 0
> > > >
> > > > This is due to
> > > >
> > > >     get_abs_timeout(&req.timeout, 5000000000);
> > > >
> > > > in etna_bo_cpu_prep which can exceed NSEC_PER_SEC.
> > > >
> > > > Should i send a patch to revert that change since it breaks existing userspace?
> > >
> > > No need to revert. This patch has not been applied to the etnaviv tree
> > > yet, I guess it's just in one of Arnds branches feeding into -next.
> > >
> > > That part of userspace is pretty dumb, as it misses to renormalize
> > > tv_nsec when it overflows the second boundary. So if what I see is
> > > correct it should be enough to allow 2 * NSEC_PER_SEC, which should
> > > both reject broken large timeout and keep existing userspace working.
> >
> > Ah, so it's never more than 2 billion nanoseconds in known user space?
> > I can definitely change my patch (actually add one on top) to allow that
> > and handle it as before, or alternatively accept any 64-bit nanosecond value
> > as arm64 already did, but make it less inefficient to handle.
>
> So the broken userspace code looks like this:
>
> static inline void get_abs_timeout(struct drm_etnaviv_timespec *tv, uint64_t ns)
> {
>         struct timespec t;
>         uint32_t s = ns / 1000000000;
>         clock_gettime(CLOCK_MONOTONIC, &t);
>         tv->tv_sec = t.tv_sec + s;
>         tv->tv_nsec = t.tv_nsec + ns - (s * 1000000000);
> }
>
> Which means it _tries_ to do the right thing by putting the billion
> part into the tv_sec member and only the remaining ns part is added to
> tv_nsec, but then it fails to propagate a tv_nsec overflow over
> NSEC_PER_SEC into tv_sec.
>
> Which means the tv_nsec should never be more than 2 * NSEC_PER_SEC in
> known userspace. I would prefer if we could make the interface as
> strict as possible (i.e. no arbitrary large numbers in tv_nsec), while
> keeping this specific corner case working.

I've added a patch on top of my 2038 branch, please have a look at that.

      Arnd

Patch

diff --git a/drivers/gpu/drm/etnaviv/etnaviv_drv.c b/drivers/gpu/drm/etnaviv/etnaviv_drv.c
index 1f9c01be40d7..95d72dc00280 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_drv.c
+++ b/drivers/gpu/drm/etnaviv/etnaviv_drv.c
@@ -297,6 +297,9 @@  static int etnaviv_ioctl_gem_cpu_prep(struct drm_device *dev, void *data,
 	if (args->op & ~(ETNA_PREP_READ | ETNA_PREP_WRITE | ETNA_PREP_NOSYNC))
 		return -EINVAL;
 
+	if (args->timeout.tv_nsec > NSEC_PER_SEC)
+		return -EINVAL;
+
 	obj = drm_gem_object_lookup(file, args->handle);
 	if (!obj)
 		return -ENOENT;
@@ -360,6 +363,9 @@  static int etnaviv_ioctl_wait_fence(struct drm_device *dev, void *data,
 	if (args->flags & ~(ETNA_WAIT_NONBLOCK))
 		return -EINVAL;
 
+	if (args->timeout.tv_nsec > NSEC_PER_SEC)
+		return -EINVAL;
+
 	if (args->pipe >= ETNA_MAX_PIPES)
 		return -EINVAL;
 
@@ -411,6 +417,9 @@  static int etnaviv_ioctl_gem_wait(struct drm_device *dev, void *data,
 	if (args->flags & ~(ETNA_WAIT_NONBLOCK))
 		return -EINVAL;
 
+	if (args->timeout.tv_nsec > NSEC_PER_SEC)
+		return -EINVAL;
+
 	if (args->pipe >= ETNA_MAX_PIPES)
 		return -EINVAL;