Though we do check the event ring read pointer by "is_valid_ring_ptr"
to make sure it is in the buffer range, but there is another risk the
pointer may be not aligned. Since we are expecting event ring elements
are 128 bits(struct mhi_tre) aligned, an unaligned read pointer could lead
to multiple issues like DoS or ring buffer memory corruption.
So add a alignment check for event ring read pointer.
Signed-off-by: Krishna chaitanya chundru <[email protected]>
---
drivers/bus/mhi/host/main.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/bus/mhi/host/main.c b/drivers/bus/mhi/host/main.c
index 499590437e9b..c907bbb67fb2 100644
--- a/drivers/bus/mhi/host/main.c
+++ b/drivers/bus/mhi/host/main.c
@@ -268,7 +268,7 @@ static void mhi_del_ring_element(struct mhi_controller *mhi_cntrl,
static bool is_valid_ring_ptr(struct mhi_ring *ring, dma_addr_t addr)
{
- return addr >= ring->iommu_base && addr < ring->iommu_base + ring->len;
+ return addr >= ring->iommu_base && addr < ring->iommu_base + ring->len && addr % 16 == 0;
}
int mhi_destroy_device(struct device *dev, void *data)
---
base-commit: 71e68e182e382e951d6248bccc3c960dcec5a718
change-id: 20231013-alignment_check-c013f509d24a
Best regards,
--
Krishna chaitanya chundru <[email protected]>
On Mon, Oct 23, 2023 at 03:13:06PM +0530, Krishna chaitanya chundru wrote:
> Though we do check the event ring read pointer by "is_valid_ring_ptr"
> to make sure it is in the buffer range, but there is another risk the
> pointer may be not aligned. Since we are expecting event ring elements
> are 128 bits(struct mhi_tre) aligned, an unaligned read pointer could lead
> to multiple issues like DoS or ring buffer memory corruption.
>
> So add a alignment check for event ring read pointer.
>
> Signed-off-by: Krishna chaitanya chundru <[email protected]>
Reviewed-by: Bjorn Andersson <[email protected]>
Regards,
Bjorn
> ---
> drivers/bus/mhi/host/main.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/bus/mhi/host/main.c b/drivers/bus/mhi/host/main.c
> index 499590437e9b..c907bbb67fb2 100644
> --- a/drivers/bus/mhi/host/main.c
> +++ b/drivers/bus/mhi/host/main.c
> @@ -268,7 +268,7 @@ static void mhi_del_ring_element(struct mhi_controller *mhi_cntrl,
>
> static bool is_valid_ring_ptr(struct mhi_ring *ring, dma_addr_t addr)
> {
> - return addr >= ring->iommu_base && addr < ring->iommu_base + ring->len;
> + return addr >= ring->iommu_base && addr < ring->iommu_base + ring->len && addr % 16 == 0;
> }
>
> int mhi_destroy_device(struct device *dev, void *data)
>
> ---
> base-commit: 71e68e182e382e951d6248bccc3c960dcec5a718
> change-id: 20231013-alignment_check-c013f509d24a
>
> Best regards,
> --
> Krishna chaitanya chundru <[email protected]>
>
On Mon, Oct 23, 2023 at 03:13:06PM +0530, Krishna chaitanya chundru wrote:
> Though we do check the event ring read pointer by "is_valid_ring_ptr"
> to make sure it is in the buffer range, but there is another risk the
> pointer may be not aligned. Since we are expecting event ring elements
> are 128 bits(struct mhi_tre) aligned, an unaligned read pointer could lead
"mhi_tre" got renamed to "mhi_ring_element"
> to multiple issues like DoS or ring buffer memory corruption.
>
> So add a alignment check for event ring read pointer.
>
Since this is a potential fix, you should add the fixes tag and CC stable.
> Signed-off-by: Krishna chaitanya chundru <[email protected]>
> ---
> drivers/bus/mhi/host/main.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/bus/mhi/host/main.c b/drivers/bus/mhi/host/main.c
> index 499590437e9b..c907bbb67fb2 100644
> --- a/drivers/bus/mhi/host/main.c
> +++ b/drivers/bus/mhi/host/main.c
> @@ -268,7 +268,7 @@ static void mhi_del_ring_element(struct mhi_controller *mhi_cntrl,
>
> static bool is_valid_ring_ptr(struct mhi_ring *ring, dma_addr_t addr)
> {
> - return addr >= ring->iommu_base && addr < ring->iommu_base + ring->len;
> + return addr >= ring->iommu_base && addr < ring->iommu_base + ring->len && addr % 16 == 0;
How about,
!(addr % 16)
- Mani
> }
>
> int mhi_destroy_device(struct device *dev, void *data)
>
> ---
> base-commit: 71e68e182e382e951d6248bccc3c960dcec5a718
> change-id: 20231013-alignment_check-c013f509d24a
>
> Best regards,
> --
> Krishna chaitanya chundru <[email protected]>
>
--
மணிவண்ணன் சதாசிவம்
On 10/27/2023 7:09 AM, Manivannan Sadhasivam wrote:
> On Mon, Oct 23, 2023 at 03:13:06PM +0530, Krishna chaitanya chundru wrote:
>> Though we do check the event ring read pointer by "is_valid_ring_ptr"
>> to make sure it is in the buffer range, but there is another risk the
>> pointer may be not aligned. Since we are expecting event ring elements
>> are 128 bits(struct mhi_tre) aligned, an unaligned read pointer could lead
>
> "mhi_tre" got renamed to "mhi_ring_element"
>
>> to multiple issues like DoS or ring buffer memory corruption.
>>
>> So add a alignment check for event ring read pointer.
>>
>
> Since this is a potential fix, you should add the fixes tag and CC stable.
>
>> Signed-off-by: Krishna chaitanya chundru <[email protected]>
>> ---
>> drivers/bus/mhi/host/main.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/bus/mhi/host/main.c b/drivers/bus/mhi/host/main.c
>> index 499590437e9b..c907bbb67fb2 100644
>> --- a/drivers/bus/mhi/host/main.c
>> +++ b/drivers/bus/mhi/host/main.c
>> @@ -268,7 +268,7 @@ static void mhi_del_ring_element(struct mhi_controller *mhi_cntrl,
>>
>> static bool is_valid_ring_ptr(struct mhi_ring *ring, dma_addr_t addr)
>> {
>> - return addr >= ring->iommu_base && addr < ring->iommu_base + ring->len;
>> + return addr >= ring->iommu_base && addr < ring->iommu_base + ring->len && addr % 16 == 0;
>
> How about,
>
> !(addr % 16)
We are guaranteed that the ring allocation is 16 byte aligned, right?
I think using "struct mhi_ring_element" instead of "16" would be better.
I'm also thinking that perhaps doing a bit-wise & with a mask would be
better than the % operator. Not only is that how these alignment checks
seem to normally be done elsewhere, but this check is in a critical
patch for the MHI stack.
-Jeff
On Fri, Oct 27, 2023 at 08:19:44AM -0600, Jeffrey Hugo wrote:
> On 10/27/2023 7:09 AM, Manivannan Sadhasivam wrote:
> > On Mon, Oct 23, 2023 at 03:13:06PM +0530, Krishna chaitanya chundru wrote:
> > > Though we do check the event ring read pointer by "is_valid_ring_ptr"
> > > to make sure it is in the buffer range, but there is another risk the
> > > pointer may be not aligned. Since we are expecting event ring elements
> > > are 128 bits(struct mhi_tre) aligned, an unaligned read pointer could lead
> >
> > "mhi_tre" got renamed to "mhi_ring_element"
> >
> > > to multiple issues like DoS or ring buffer memory corruption.
> > >
> > > So add a alignment check for event ring read pointer.
> > >
> >
> > Since this is a potential fix, you should add the fixes tag and CC stable.
> >
> > > Signed-off-by: Krishna chaitanya chundru <[email protected]>
> > > ---
> > > drivers/bus/mhi/host/main.c | 2 +-
> > > 1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/bus/mhi/host/main.c b/drivers/bus/mhi/host/main.c
> > > index 499590437e9b..c907bbb67fb2 100644
> > > --- a/drivers/bus/mhi/host/main.c
> > > +++ b/drivers/bus/mhi/host/main.c
> > > @@ -268,7 +268,7 @@ static void mhi_del_ring_element(struct mhi_controller *mhi_cntrl,
> > > static bool is_valid_ring_ptr(struct mhi_ring *ring, dma_addr_t addr)
> > > {
> > > - return addr >= ring->iommu_base && addr < ring->iommu_base + ring->len;
> > > + return addr >= ring->iommu_base && addr < ring->iommu_base + ring->len && addr % 16 == 0;
> >
> > How about,
> >
> > !(addr % 16)
>
> We are guaranteed that the ring allocation is 16 byte aligned, right?
>
> I think using "struct mhi_ring_element" instead of "16" would be better.
>
> I'm also thinking that perhaps doing a bit-wise & with a mask would be
> better than the % operator. Not only is that how these alignment checks
> seem to normally be done elsewhere, but this check is in a critical patch
> for the MHI stack.
>
Yes, both of your suggestions sounds good to me.
Chaitanya, please use below check:
!(addr & (sizeof(struct mhi_ring_element) - 1))
- Mani
> -Jeff
>
--
மணிவண்ணன் சதாசிவம்
On 10/29/2023 12:56 PM, Manivannan Sadhasivam wrote:
> On Fri, Oct 27, 2023 at 08:19:44AM -0600, Jeffrey Hugo wrote:
>> On 10/27/2023 7:09 AM, Manivannan Sadhasivam wrote:
>>> On Mon, Oct 23, 2023 at 03:13:06PM +0530, Krishna chaitanya chundru wrote:
>>>> Though we do check the event ring read pointer by "is_valid_ring_ptr"
>>>> to make sure it is in the buffer range, but there is another risk the
>>>> pointer may be not aligned. Since we are expecting event ring elements
>>>> are 128 bits(struct mhi_tre) aligned, an unaligned read pointer could lead
>>> "mhi_tre" got renamed to "mhi_ring_element"
>>>
>>>> to multiple issues like DoS or ring buffer memory corruption.
>>>>
>>>> So add a alignment check for event ring read pointer.
>>>>
>>> Since this is a potential fix, you should add the fixes tag and CC stable.
>>>
>>>> Signed-off-by: Krishna chaitanya chundru <[email protected]>
>>>> ---
>>>> drivers/bus/mhi/host/main.c | 2 +-
>>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/bus/mhi/host/main.c b/drivers/bus/mhi/host/main.c
>>>> index 499590437e9b..c907bbb67fb2 100644
>>>> --- a/drivers/bus/mhi/host/main.c
>>>> +++ b/drivers/bus/mhi/host/main.c
>>>> @@ -268,7 +268,7 @@ static void mhi_del_ring_element(struct mhi_controller *mhi_cntrl,
>>>> static bool is_valid_ring_ptr(struct mhi_ring *ring, dma_addr_t addr)
>>>> {
>>>> - return addr >= ring->iommu_base && addr < ring->iommu_base + ring->len;
>>>> + return addr >= ring->iommu_base && addr < ring->iommu_base + ring->len && addr % 16 == 0;
>>> How about,
>>>
>>> !(addr % 16)
>> We are guaranteed that the ring allocation is 16 byte aligned, right?
>>
>> I think using "struct mhi_ring_element" instead of "16" would be better.
>>
>> I'm also thinking that perhaps doing a bit-wise & with a mask would be
>> better than the % operator. Not only is that how these alignment checks
>> seem to normally be done elsewhere, but this check is in a critical patch
>> for the MHI stack.
>>
> Yes, both of your suggestions sounds good to me.
>
> Chaitanya, please use below check:
>
> !(addr & (sizeof(struct mhi_ring_element) - 1))
>
> - Mani
I will update in the next patch.
- Krishna Chaitanya.
>> -Jeff
>>