[PATCH] iommu/io-pgtable-arm: Fix IOVA validation for 32-bit

[PATCH] iommu/io-pgtable-arm: Fix IOVA validation for 32-bit

[Robin Murphy]

Since we ony support the TTB1 quirk for AArch64 contexts, and
consequently only for 64-bit builds, the sign-extension aspect of the
"are all bits above IAS consistent?" check should implicitly only apply
to 64-bit IOVAs. Change the type of the cast to ensure that 32-bit longs
don't inadvertently get sign-extended, and thus considered invalid, if
they happen to be above 2GB in the TTB0 region.

Reported-by: Stephan Gerhold <stephan@gerhold.net>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>

---

Logically there may also have been a UBSAN "shift greater than size of
type" warning too, but arch/arm doesn't support UBSAN_SANITIZE_ALL,
and that's now my only easy "spin up a 32-bit VM" option to hand :)

 drivers/iommu/io-pgtable-arm.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
index 983b08477e64..04fbd4bf0ff9 100644
--- a/drivers/iommu/io-pgtable-arm.c
+++ b/drivers/iommu/io-pgtable-arm.c
@@ -468,7 +468,7 @@ static int arm_lpae_map(struct io_pgtable_ops *ops, unsigned long iova,
 	arm_lpae_iopte *ptep = data->pgd;
 	int ret, lvl = data->start_level;
 	arm_lpae_iopte prot;
-	long iaext = (long)iova >> cfg->ias;
+	long iaext = (s64)iova >> cfg->ias;
 
 	/* If no access, then nothing to do */
 	if (!(iommu_prot & (IOMMU_READ | IOMMU_WRITE)))
@@ -645,7 +645,7 @@ static size_t arm_lpae_unmap(struct io_pgtable_ops *ops, unsigned long iova,
 	struct arm_lpae_io_pgtable *data = io_pgtable_ops_to_data(ops);
 	struct io_pgtable_cfg *cfg = &data->iop.cfg;
 	arm_lpae_iopte *ptep = data->pgd;
-	long iaext = (long)iova >> cfg->ias;
+	long iaext = (s64)iova >> cfg->ias;
 
 	if (WARN_ON(!size || (size & cfg->pgsize_bitmap) != size))
 		return 0;
-- 
2.23.0.dirty


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Re: [PATCH] iommu/io-pgtable-arm: Fix IOVA validation for 32-bit

[Will Deacon]

On Fri, Feb 28, 2020 at 02:18:55PM +0000, Robin Murphy wrote:
> Since we ony support the TTB1 quirk for AArch64 contexts, and
> consequently only for 64-bit builds, the sign-extension aspect of the
> "are all bits above IAS consistent?" check should implicitly only apply
> to 64-bit IOVAs. Change the type of the cast to ensure that 32-bit longs
> don't inadvertently get sign-extended, and thus considered invalid, if
> they happen to be above 2GB in the TTB0 region.
> 
> Reported-by: Stephan Gerhold <stephan@gerhold.net>
> Signed-off-by: Robin Murphy <robin.murphy@arm.com>
> 
> ---
> 
> Logically there may also have been a UBSAN "shift greater than size of
> type" warning too, but arch/arm doesn't support UBSAN_SANITIZE_ALL,
> and that's now my only easy "spin up a 32-bit VM" option to hand :)
> 
>  drivers/iommu/io-pgtable-arm.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)

Acked-by: Will Deacon <will@kernel.org>

Joerg -- pleae can you take this as a fix for 5.6?

Thanks,

Will

> diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
> index 983b08477e64..04fbd4bf0ff9 100644
> --- a/drivers/iommu/io-pgtable-arm.c
> +++ b/drivers/iommu/io-pgtable-arm.c
> @@ -468,7 +468,7 @@ static int arm_lpae_map(struct io_pgtable_ops *ops, unsigned long iova,
>  	arm_lpae_iopte *ptep = data->pgd;
>  	int ret, lvl = data->start_level;
>  	arm_lpae_iopte prot;
> -	long iaext = (long)iova >> cfg->ias;
> +	long iaext = (s64)iova >> cfg->ias;
>  
>  	/* If no access, then nothing to do */
>  	if (!(iommu_prot & (IOMMU_READ | IOMMU_WRITE)))
> @@ -645,7 +645,7 @@ static size_t arm_lpae_unmap(struct io_pgtable_ops *ops, unsigned long iova,
>  	struct arm_lpae_io_pgtable *data = io_pgtable_ops_to_data(ops);
>  	struct io_pgtable_cfg *cfg = &data->iop.cfg;
>  	arm_lpae_iopte *ptep = data->pgd;
> -	long iaext = (long)iova >> cfg->ias;
> +	long iaext = (s64)iova >> cfg->ias;
>  
>  	if (WARN_ON(!size || (size & cfg->pgsize_bitmap) != size))
>  		return 0;
> -- 
> 2.23.0.dirty
> 

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Re: [PATCH] iommu/io-pgtable-arm: Fix IOVA validation for 32-bit

[Joerg Roedel]

On Mon, Mar 02, 2020 at 11:53:01AM +0000, Will Deacon wrote:
> On Fri, Feb 28, 2020 at 02:18:55PM +0000, Robin Murphy wrote:
> > Since we ony support the TTB1 quirk for AArch64 contexts, and
> > consequently only for 64-bit builds, the sign-extension aspect of the
> > "are all bits above IAS consistent?" check should implicitly only apply
> > to 64-bit IOVAs. Change the type of the cast to ensure that 32-bit longs
> > don't inadvertently get sign-extended, and thus considered invalid, if
> > they happen to be above 2GB in the TTB0 region.
> > 
> > Reported-by: Stephan Gerhold <stephan@gerhold.net>
> > Signed-off-by: Robin Murphy <robin.murphy@arm.com>
> > 
> > ---
> > 
> > Logically there may also have been a UBSAN "shift greater than size of
> > type" warning too, but arch/arm doesn't support UBSAN_SANITIZE_ALL,
> > and that's now my only easy "spin up a 32-bit VM" option to hand :)
> > 
> >  drivers/iommu/io-pgtable-arm.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> Acked-by: Will Deacon <will@kernel.org>
> 
> Joerg -- pleae can you take this as a fix for 5.6?

Done, do you also have a fixes-tag for me?

Regards,

	Joerg


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Re: [PATCH] iommu/io-pgtable-arm: Fix IOVA validation for 32-bit

[Will Deacon]

On Mon, Mar 02, 2020 at 05:11:23PM +0100, Joerg Roedel wrote:
> On Mon, Mar 02, 2020 at 11:53:01AM +0000, Will Deacon wrote:
> > On Fri, Feb 28, 2020 at 02:18:55PM +0000, Robin Murphy wrote:
> > > Since we ony support the TTB1 quirk for AArch64 contexts, and
> > > consequently only for 64-bit builds, the sign-extension aspect of the
> > > "are all bits above IAS consistent?" check should implicitly only apply
> > > to 64-bit IOVAs. Change the type of the cast to ensure that 32-bit longs
> > > don't inadvertently get sign-extended, and thus considered invalid, if
> > > they happen to be above 2GB in the TTB0 region.
> > > 
> > > Reported-by: Stephan Gerhold <stephan@gerhold.net>
> > > Signed-off-by: Robin Murphy <robin.murphy@arm.com>
> > > 
> > > ---
> > > 
> > > Logically there may also have been a UBSAN "shift greater than size of
> > > type" warning too, but arch/arm doesn't support UBSAN_SANITIZE_ALL,
> > > and that's now my only easy "spin up a 32-bit VM" option to hand :)
> > > 
> > >  drivers/iommu/io-pgtable-arm.c | 4 ++--
> > >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > Acked-by: Will Deacon <will@kernel.org>
> > 
> > Joerg -- pleae can you take this as a fix for 5.6?
> 
> Done, do you also have a fixes-tag for me?

Fixes: db6903010aa5 ("iommu/io-pgtable-arm: Prepare for TTBR1 usage")

Although it doesn't need to go to -stable, since this was only introduced
during the recent merge window.

Will

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Re: [PATCH] iommu/io-pgtable-arm: Fix IOVA validation for 32-bit

[Stephan Gerhold]

Hi Robin,

On Fri, Feb 28, 2020 at 02:18:55PM +0000, Robin Murphy wrote:
> Since we ony support the TTB1 quirk for AArch64 contexts, and
> consequently only for 64-bit builds, the sign-extension aspect of the
> "are all bits above IAS consistent?" check should implicitly only apply
> to 64-bit IOVAs. Change the type of the cast to ensure that 32-bit longs
> don't inadvertently get sign-extended, and thus considered invalid, if
> they happen to be above 2GB in the TTB0 region.
> 
> Reported-by: Stephan Gerhold <stephan@gerhold.net>
> Signed-off-by: Robin Murphy <robin.murphy@arm.com>
> 

Thanks for the patch!

Just wanted to report that this patch does indeed fix the problem
I had with qcom-venus on ARM32.

It's probably too late now, but FWIW:
Tested-by: Stephan Gerhold <stephan@gerhold.net>

> ---
> 
> Logically there may also have been a UBSAN "shift greater than size of
> type" warning too, but arch/arm doesn't support UBSAN_SANITIZE_ALL,
> and that's now my only easy "spin up a 32-bit VM" option to hand :)
> 
>  drivers/iommu/io-pgtable-arm.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
> index 983b08477e64..04fbd4bf0ff9 100644
> --- a/drivers/iommu/io-pgtable-arm.c
> +++ b/drivers/iommu/io-pgtable-arm.c
> @@ -468,7 +468,7 @@ static int arm_lpae_map(struct io_pgtable_ops *ops, unsigned long iova,
>  	arm_lpae_iopte *ptep = data->pgd;
>  	int ret, lvl = data->start_level;
>  	arm_lpae_iopte prot;
> -	long iaext = (long)iova >> cfg->ias;
> +	long iaext = (s64)iova >> cfg->ias;
>  
>  	/* If no access, then nothing to do */
>  	if (!(iommu_prot & (IOMMU_READ | IOMMU_WRITE)))
> @@ -645,7 +645,7 @@ static size_t arm_lpae_unmap(struct io_pgtable_ops *ops, unsigned long iova,
>  	struct arm_lpae_io_pgtable *data = io_pgtable_ops_to_data(ops);
>  	struct io_pgtable_cfg *cfg = &data->iop.cfg;
>  	arm_lpae_iopte *ptep = data->pgd;
> -	long iaext = (long)iova >> cfg->ias;
> +	long iaext = (s64)iova >> cfg->ias;
>  
>  	if (WARN_ON(!size || (size & cfg->pgsize_bitmap) != size))
>  		return 0;
> -- 
> 2.23.0.dirty
> 

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