2024-01-28 11:28:02

by Erick Archer

Subject: [PATCH v2] bus: mhi: ep: Use kcalloc() instead of kzalloc()

This is an effort to get rid of all multiplications from allocation
functions in order to prevent integer overflows [1].

Here the multiplication is obviously safe because the "event_rings"
member never can have a value greater than 255 (8 bits). This member
is set twice using always FIELD_GET:

mhi_cntrl->event_rings = FIELD_GET(MHICFG_NER_MASK, regval);
mhi_cntrl->event_rings = FIELD_GET(MHICFG_NER_MASK, regval);

And the MHICFG_NER_MASK macro defines the 8 bits mask that guarantees
a maximum value of 255.

However, using kcalloc() is more appropriate [1] and improves
readability. This patch has no effect on runtime behavior.

Link: https://github.com/KSPP/linux/issues/162 [1]
Link: https://www.kernel.org/doc/html/next/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments [1]
Reviewed-by: Gustavo A. R. Silva <[email protected]>
Signed-off-by: Erick Archer <[email protected]>
---
Changes in v2:
- Add more info in the commit message to better explain the change.
(Dan Carpenter)
- Add the "Reviewed-by:" tag.

Previous versions:
v1 - https://lore.kernel.org/linux-hardening/[email protected]/
---
drivers/bus/mhi/ep/main.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/bus/mhi/ep/main.c b/drivers/bus/mhi/ep/main.c
index 65fc1d738bec..8d7a4102bdb7 100644
--- a/drivers/bus/mhi/ep/main.c
+++ b/drivers/bus/mhi/ep/main.c
@@ -1149,8 +1149,9 @@ int mhi_ep_power_up(struct mhi_ep_cntrl *mhi_cntrl)
mhi_ep_mmio_mask_interrupts(mhi_cntrl);
mhi_ep_mmio_init(mhi_cntrl);

- mhi_cntrl->mhi_event = kzalloc(mhi_cntrl->event_rings * (sizeof(*mhi_cntrl->mhi_event)),
- GFP_KERNEL);
+ mhi_cntrl->mhi_event = kcalloc(mhi_cntrl->event_rings,
+ sizeof(*mhi_cntrl->mhi_event),
+ GFP_KERNEL);
if (!mhi_cntrl->mhi_event)
return -ENOMEM;

--
2.25.1

2024-01-30 08:36:09

by Manivannan Sadhasivam

Subject: Re: [PATCH v2] bus: mhi: ep: Use kcalloc() instead of kzalloc()

On Sun, Jan 28, 2024 at 12:27:22PM +0100, Erick Archer wrote:
> This is an effort to get rid of all multiplications from allocation
> functions in order to prevent integer overflows [1].
>
> Here the multiplication is obviously safe because the "event_rings"
> member never can have a value greater than 255 (8 bits). This member
> is set twice using always FIELD_GET:
>
> mhi_cntrl->event_rings = FIELD_GET(MHICFG_NER_MASK, regval);
> mhi_cntrl->event_rings = FIELD_GET(MHICFG_NER_MASK, regval);
>
> And the MHICFG_NER_MASK macro defines the 8 bits mask that guarantees
> a maximum value of 255.
>
> However, using kcalloc() is more appropriate [1] and improves
> readability. This patch has no effect on runtime behavior.
>
> Link: https://github.com/KSPP/linux/issues/162 [1]
> Link: https://www.kernel.org/doc/html/next/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments [1]
> Reviewed-by: Gustavo A. R. Silva <[email protected]>
> Signed-off-by: Erick Archer <[email protected]>

Reviewed-by: Manivannan Sadhasivam <[email protected]>

- Mani

> ---
> Changes in v2:
> - Add more info in the commit message to better explain the change.
> (Dan Carpenter)
> - Add the "Reviewed-by:" tag.
>
> Previous versions:
> v1 - https://lore.kernel.org/linux-hardening/[email protected]/
> ---
> drivers/bus/mhi/ep/main.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/bus/mhi/ep/main.c b/drivers/bus/mhi/ep/main.c
> index 65fc1d738bec..8d7a4102bdb7 100644
> --- a/drivers/bus/mhi/ep/main.c
> +++ b/drivers/bus/mhi/ep/main.c
> @@ -1149,8 +1149,9 @@ int mhi_ep_power_up(struct mhi_ep_cntrl *mhi_cntrl)
> mhi_ep_mmio_mask_interrupts(mhi_cntrl);
> mhi_ep_mmio_init(mhi_cntrl);
>
> - mhi_cntrl->mhi_event = kzalloc(mhi_cntrl->event_rings * (sizeof(*mhi_cntrl->mhi_event)),
> - GFP_KERNEL);
> + mhi_cntrl->mhi_event = kcalloc(mhi_cntrl->event_rings,
> + sizeof(*mhi_cntrl->mhi_event),
> + GFP_KERNEL);
> if (!mhi_cntrl->mhi_event)
> return -ENOMEM;
>
> --
> 2.25.1
>

--
மணிவண்ணன் சதாசிவம்

2024-01-30 11:24:18

by Alex Elder

Subject: Re: [PATCH v2] bus: mhi: ep: Use kcalloc() instead of kzalloc()

On 1/28/24 5:27 AM, Erick Archer wrote:
> This is an effort to get rid of all multiplications from allocation
> functions in order to prevent integer overflows [1].
>
> Here the multiplication is obviously safe because the "event_rings"
> member never can have a value greater than 255 (8 bits). This member
> is set twice using always FIELD_GET:
>
> mhi_cntrl->event_rings = FIELD_GET(MHICFG_NER_MASK, regval);
> mhi_cntrl->event_rings = FIELD_GET(MHICFG_NER_MASK, regval);
>
> And the MHICFG_NER_MASK macro defines the 8 bits mask that guarantees
> a maximum value of 255.
>
> However, using kcalloc() is more appropriate [1] and improves
> readability. This patch has no effect on runtime behavior.
>
> Link: https://github.com/KSPP/linux/issues/162 [1]
> Link: https://www.kernel.org/doc/html/next/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments [1]
> Reviewed-by: Gustavo A. R. Silva <[email protected]>
> Signed-off-by: Erick Archer <[email protected]>
> ---
> Changes in v2:
> - Add more info in the commit message to better explain the change.
> (Dan Carpenter)
> - Add the "Reviewed-by:" tag.

Looks good.

Reviewed-by: Alex Elder <[email protected]>

>
> Previous versions:
> v1 - https://lore.kernel.org/linux-hardening/[email protected]/
> ---
> drivers/bus/mhi/ep/main.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/bus/mhi/ep/main.c b/drivers/bus/mhi/ep/main.c
> index 65fc1d738bec..8d7a4102bdb7 100644
> --- a/drivers/bus/mhi/ep/main.c
> +++ b/drivers/bus/mhi/ep/main.c
> @@ -1149,8 +1149,9 @@ int mhi_ep_power_up(struct mhi_ep_cntrl *mhi_cntrl)
> mhi_ep_mmio_mask_interrupts(mhi_cntrl);
> mhi_ep_mmio_init(mhi_cntrl);
>
> - mhi_cntrl->mhi_event = kzalloc(mhi_cntrl->event_rings * (sizeof(*mhi_cntrl->mhi_event)),
> - GFP_KERNEL);
> + mhi_cntrl->mhi_event = kcalloc(mhi_cntrl->event_rings,
> + sizeof(*mhi_cntrl->mhi_event),
> + GFP_KERNEL);
> if (!mhi_cntrl->mhi_event)
> return -ENOMEM;
>
> --
> 2.25.1
>

2024-02-03 04:57:13

by Manivannan Sadhasivam

Subject: Re: [PATCH v2] bus: mhi: ep: Use kcalloc() instead of kzalloc()

On Sun, Jan 28, 2024 at 12:27:22PM +0100, Erick Archer wrote:
> This is an effort to get rid of all multiplications from allocation
> functions in order to prevent integer overflows [1].
>
> Here the multiplication is obviously safe because the "event_rings"
> member never can have a value greater than 255 (8 bits). This member
> is set twice using always FIELD_GET:
>
> mhi_cntrl->event_rings = FIELD_GET(MHICFG_NER_MASK, regval);
> mhi_cntrl->event_rings = FIELD_GET(MHICFG_NER_MASK, regval);
>
> And the MHICFG_NER_MASK macro defines the 8 bits mask that guarantees
> a maximum value of 255.
>
> However, using kcalloc() is more appropriate [1] and improves
> readability. This patch has no effect on runtime behavior.
>
> Link: https://github.com/KSPP/linux/issues/162 [1]
> Link: https://www.kernel.org/doc/html/next/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments [1]
> Reviewed-by: Gustavo A. R. Silva <[email protected]>
> Signed-off-by: Erick Archer <[email protected]>

Applied to mhi-next!

- Mani

> ---
> Changes in v2:
> - Add more info in the commit message to better explain the change.
> (Dan Carpenter)
> - Add the "Reviewed-by:" tag.
>
> Previous versions:
> v1 - https://lore.kernel.org/linux-hardening/[email protected]/
> ---
> drivers/bus/mhi/ep/main.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/bus/mhi/ep/main.c b/drivers/bus/mhi/ep/main.c
> index 65fc1d738bec..8d7a4102bdb7 100644
> --- a/drivers/bus/mhi/ep/main.c
> +++ b/drivers/bus/mhi/ep/main.c
> @@ -1149,8 +1149,9 @@ int mhi_ep_power_up(struct mhi_ep_cntrl *mhi_cntrl)
> mhi_ep_mmio_mask_interrupts(mhi_cntrl);
> mhi_ep_mmio_init(mhi_cntrl);
>
> - mhi_cntrl->mhi_event = kzalloc(mhi_cntrl->event_rings * (sizeof(*mhi_cntrl->mhi_event)),
> - GFP_KERNEL);
> + mhi_cntrl->mhi_event = kcalloc(mhi_cntrl->event_rings,
> + sizeof(*mhi_cntrl->mhi_event),
> + GFP_KERNEL);
> if (!mhi_cntrl->mhi_event)
> return -ENOMEM;
>
> --
> 2.25.1
>

--
மணிவண்ணன் சதாசிவம்