[PATCH] virt: acrn: Prefer array_syze and struct_size over open coded arithmetic

[PATCH] virt: acrn: Prefer array_syze and struct_size over open coded arithmetic

[Len Baker]

As noted in the "Deprecated Interfaces, Language Features, Attributes,
and Conventions" documentation [1], size calculations (especially
multiplication) should not be performed in memory allocator (or similar)
function arguments due to the risk of them overflowing. This could lead
to values wrapping around and a smaller allocation being made than the
caller was expecting. Using those allocations could lead to linear
overflows of heap memory and other misbehaviors.

So, use the array_size() helper to do the arithmetic instead of the
argument "count * size" in the vzalloc() function.

Also, take the opportunity to add a flexible array member of struct
vm_memory_region_op to the vm_memory_region_batch structure. And then,
change the code accordingly and use the struct_size() helper to do the
arithmetic instead of the argument "size + size * count" in the kzalloc
function.

This code was detected with the help of Coccinelle and audited and fixed
manually.

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments

Signed-off-by: Len Baker <len.baker@gmx.com>
---
 drivers/virt/acrn/acrn_drv.h | 10 ++++++----
 drivers/virt/acrn/mm.c       |  9 ++++-----
 2 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/drivers/virt/acrn/acrn_drv.h b/drivers/virt/acrn/acrn_drv.h
index 1be54efa666c..fcc2e3e5232a 100644
--- a/drivers/virt/acrn/acrn_drv.h
+++ b/drivers/virt/acrn/acrn_drv.h
@@ -48,6 +48,7 @@ struct vm_memory_region_op {
  * @reserved:		Reserved.
  * @regions_num:	The number of vm_memory_region_op.
  * @regions_gpa:	Physical address of a vm_memory_region_op array.
+ * @regions_op:		Flexible array of vm_memory_region_op.
  *
  * HC_VM_SET_MEMORY_REGIONS uses this structure to manage EPT mappings of
  * multiple memory regions of a User VM. A &struct vm_memory_region_batch
@@ -55,10 +56,11 @@ struct vm_memory_region_op {
  * ACRN Hypervisor.
  */
 struct vm_memory_region_batch {
-	u16	vmid;
-	u16	reserved[3];
-	u32	regions_num;
-	u64	regions_gpa;
+	u16				vmid;
+	u16				reserved[3];
+	u32				regions_num;
+	u64				regions_gpa;
+	struct vm_memory_region_op	regions_op[];
 };

 /**
diff --git a/drivers/virt/acrn/mm.c b/drivers/virt/acrn/mm.c
index c4f2e15c8a2b..a881742cd48d 100644
--- a/drivers/virt/acrn/mm.c
+++ b/drivers/virt/acrn/mm.c
@@ -168,7 +168,7 @@ int acrn_vm_ram_map(struct acrn_vm *vm, struct acrn_vm_memmap *memmap)

 	/* Get the page number of the map region */
 	nr_pages = memmap->len >> PAGE_SHIFT;
-	pages = vzalloc(nr_pages * sizeof(struct page *));
+	pages = vzalloc(array_size(nr_pages, sizeof(struct page *)));
 	if (!pages)
 		return -ENOMEM;

@@ -220,16 +220,15 @@ int acrn_vm_ram_map(struct acrn_vm *vm, struct acrn_vm_memmap *memmap)
 	}

 	/* Prepare the vm_memory_region_batch */
-	regions_info = kzalloc(sizeof(*regions_info) +
-			       sizeof(*vm_region) * nr_regions,
-			       GFP_KERNEL);
+	regions_info = kzalloc(struct_size(regions_info, regions_op,
+					   nr_regions), GFP_KERNEL);
 	if (!regions_info) {
 		ret = -ENOMEM;
 		goto unmap_kernel_map;
 	}

 	/* Fill each vm_memory_region_op */
-	vm_region = (struct vm_memory_region_op *)(regions_info + 1);
+	vm_region = regions_info->regions_op;
 	regions_info->vmid = vm->vmid;
 	regions_info->regions_num = nr_regions;
 	regions_info->regions_gpa = virt_to_phys(vm_region);
--
2.25.1

Re: [PATCH] virt: acrn: Prefer array_syze and struct_size over open coded arithmetic

[Li Fei1]

On Mon, Oct 11, 2021 at 12:39:02PM +0200, Len Baker wrote:
> As noted in the "Deprecated Interfaces, Language Features, Attributes,
> and Conventions" documentation [1], size calculations (especially
> multiplication) should not be performed in memory allocator (or similar)
> function arguments due to the risk of them overflowing. This could lead
> to values wrapping around and a smaller allocation being made than the
> caller was expecting. Using those allocations could lead to linear
> overflows of heap memory and other misbehaviors.
> 
> So, use the array_size() helper to do the arithmetic instead of the
> argument "count * size" in the vzalloc() function.
> 
> Also, take the opportunity to add a flexible array member of struct
> vm_memory_region_op to the vm_memory_region_batch structure. And then,
> change the code accordingly and use the struct_size() helper to do the
> arithmetic instead of the argument "size + size * count" in the kzalloc
> function.
> 
> This code was detected with the help of Coccinelle and audited and fixed
> manually.
> 
> [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments
> 
> Signed-off-by: Len Baker <len.baker@gmx.com>

Hi Baker

Thanks for helping us to fix this issue. This patch looks good to me.
Please add Signed-off-by: Fei Li <fei1.li@intel.com>.
Only two minor comments.


> ---
>  drivers/virt/acrn/acrn_drv.h | 10 ++++++----
>  drivers/virt/acrn/mm.c       |  9 ++++-----
>  2 files changed, 10 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/virt/acrn/acrn_drv.h b/drivers/virt/acrn/acrn_drv.h
> index 1be54efa666c..fcc2e3e5232a 100644
> --- a/drivers/virt/acrn/acrn_drv.h
> +++ b/drivers/virt/acrn/acrn_drv.h
> @@ -48,6 +48,7 @@ struct vm_memory_region_op {
>   * @reserved:		Reserved.
>   * @regions_num:	The number of vm_memory_region_op.
>   * @regions_gpa:	Physical address of a vm_memory_region_op array.
> + * @regions_op:		Flexible array of vm_memory_region_op.
One Tab please.
>   *
>   * HC_VM_SET_MEMORY_REGIONS uses this structure to manage EPT mappings of
>   * multiple memory regions of a User VM. A &struct vm_memory_region_batch
> @@ -55,10 +56,11 @@ struct vm_memory_region_op {
>   * ACRN Hypervisor.
>   */
>  struct vm_memory_region_batch {
> -	u16	vmid;
> -	u16	reserved[3];
> -	u32	regions_num;
> -	u64	regions_gpa;
> +	u16				vmid;
> +	u16				reserved[3];
> +	u32				regions_num;
> +	u64				regions_gpa;
> +	struct vm_memory_region_op	regions_op[];
Please use Whitespace instead of Tab.
>  };
> 
>  /**
> diff --git a/drivers/virt/acrn/mm.c b/drivers/virt/acrn/mm.c
> index c4f2e15c8a2b..a881742cd48d 100644
> --- a/drivers/virt/acrn/mm.c
> +++ b/drivers/virt/acrn/mm.c
> @@ -168,7 +168,7 @@ int acrn_vm_ram_map(struct acrn_vm *vm, struct acrn_vm_memmap *memmap)
> 
>  	/* Get the page number of the map region */
>  	nr_pages = memmap->len >> PAGE_SHIFT;
> -	pages = vzalloc(nr_pages * sizeof(struct page *));
> +	pages = vzalloc(array_size(nr_pages, sizeof(struct page *)));
>  	if (!pages)
>  		return -ENOMEM;
> 
> @@ -220,16 +220,15 @@ int acrn_vm_ram_map(struct acrn_vm *vm, struct acrn_vm_memmap *memmap)
>  	}
> 
>  	/* Prepare the vm_memory_region_batch */
> -	regions_info = kzalloc(sizeof(*regions_info) +
> -			       sizeof(*vm_region) * nr_regions,
> -			       GFP_KERNEL);
> +	regions_info = kzalloc(struct_size(regions_info, regions_op,
> +					   nr_regions), GFP_KERNEL);
>  	if (!regions_info) {
>  		ret = -ENOMEM;
>  		goto unmap_kernel_map;
>  	}
> 
>  	/* Fill each vm_memory_region_op */
> -	vm_region = (struct vm_memory_region_op *)(regions_info + 1);
> +	vm_region = regions_info->regions_op;
>  	regions_info->vmid = vm->vmid;
>  	regions_info->regions_num = nr_regions;
>  	regions_info->regions_gpa = virt_to_phys(vm_region);
> --
> 2.25.1
> 

Re: [PATCH] virt: acrn: Prefer array_syze and struct_size over open coded arithmetic

[Kees Cook]

On Tue, Oct 12, 2021 at 09:34:29AM +0800, Li Fei1 wrote:
> On Mon, Oct 11, 2021 at 12:39:02PM +0200, Len Baker wrote:
> > As noted in the "Deprecated Interfaces, Language Features, Attributes,
> > and Conventions" documentation [1], size calculations (especially
> > multiplication) should not be performed in memory allocator (or similar)
> > function arguments due to the risk of them overflowing. This could lead
> > to values wrapping around and a smaller allocation being made than the
> > caller was expecting. Using those allocations could lead to linear
> > overflows of heap memory and other misbehaviors.
> > 
> > So, use the array_size() helper to do the arithmetic instead of the
> > argument "count * size" in the vzalloc() function.
> > 
> > Also, take the opportunity to add a flexible array member of struct
> > vm_memory_region_op to the vm_memory_region_batch structure. And then,
> > change the code accordingly and use the struct_size() helper to do the
> > arithmetic instead of the argument "size + size * count" in the kzalloc
> > function.
> > 
> > This code was detected with the help of Coccinelle and audited and fixed
> > manually.
> > 
> > [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments
> > 
> > Signed-off-by: Len Baker <len.baker@gmx.com>
> 
> Hi Baker
> 
> Thanks for helping us to fix this issue. This patch looks good to me.
> Please add Signed-off-by: Fei Li <fei1.li@intel.com>.
> Only two minor comments.

For v2, please fix the Subject typo, too. :) "syze" -> "size".

-Kees

-- 
Kees Cook

Re: [PATCH] virt: acrn: Prefer array_syze and struct_size over open coded arithmetic

[Len Baker]

Hi Li,

On Tue, Oct 12, 2021 at 09:34:29AM +0800, Li Fei1 wrote:
> On Mon, Oct 11, 2021 at 12:39:02PM +0200, Len Baker wrote:
> > As noted in the "Deprecated Interfaces, Language Features, Attributes,
> > and Conventions" documentation [1], size calculations (especially
> > multiplication) should not be performed in memory allocator (or similar)
> > function arguments due to the risk of them overflowing. This could lead
> > to values wrapping around and a smaller allocation being made than the
> > caller was expecting. Using those allocations could lead to linear
> > overflows of heap memory and other misbehaviors.
> >
> > So, use the array_size() helper to do the arithmetic instead of the
> > argument "count * size" in the vzalloc() function.
> >
> > Also, take the opportunity to add a flexible array member of struct
> > vm_memory_region_op to the vm_memory_region_batch structure. And then,
> > change the code accordingly and use the struct_size() helper to do the
> > arithmetic instead of the argument "size + size * count" in the kzalloc
> > function.
> >
> > This code was detected with the help of Coccinelle and audited and fixed
> > manually.
> >
> > [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments
> >
> > Signed-off-by: Len Baker <len.baker@gmx.com>
>
> Hi Baker
>
> Thanks for helping us to fix this issue. This patch looks good to me.
> Please add Signed-off-by: Fei Li <fei1.li@intel.com>.

I can't add the "Signed-off-by" tag by myself. However, if you are in the
path to forward the patch to the mainline (maintainer's tree), you can
add by yourself the "Signed-off-by" tag before send a "pull" to Linus.
See [1] for more information.

[1] https://www.kernel.org/doc/html/latest/process/submitting-patches.html#sign-your-work-the-developer-s-certificate-of-origin

If you don't have a maintainer's tree, you can give (as a maintainer) an
"Acked-by" tag that then I can add to the patch. More info in [2].

[2] https://www.kernel.org/doc/html/latest/process/submitting-patches.html#when-to-use-acked-by-cc-and-co-developed-by

> Only two minor comments.
>
>
> > ---
> >  drivers/virt/acrn/acrn_drv.h | 10 ++++++----
> >  drivers/virt/acrn/mm.c       |  9 ++++-----
> >  2 files changed, 10 insertions(+), 9 deletions(-)
> >
> > diff --git a/drivers/virt/acrn/acrn_drv.h b/drivers/virt/acrn/acrn_drv.h
> > index 1be54efa666c..fcc2e3e5232a 100644
> > --- a/drivers/virt/acrn/acrn_drv.h
> > +++ b/drivers/virt/acrn/acrn_drv.h
> > @@ -48,6 +48,7 @@ struct vm_memory_region_op {
> >   * @reserved:		Reserved.
> >   * @regions_num:	The number of vm_memory_region_op.
> >   * @regions_gpa:	Physical address of a vm_memory_region_op array.
> > + * @regions_op:		Flexible array of vm_memory_region_op.
> One Tab please.

Sorry, but if I use only one tab, the parameters description are not all
aligned.

> >   *
> >   * HC_VM_SET_MEMORY_REGIONS uses this structure to manage EPT mappings of
> >   * multiple memory regions of a User VM. A &struct vm_memory_region_batch
> > @@ -55,10 +56,11 @@ struct vm_memory_region_op {
> >   * ACRN Hypervisor.
> >   */
> >  struct vm_memory_region_batch {
> > -	u16	vmid;
> > -	u16	reserved[3];
> > -	u32	regions_num;
> > -	u64	regions_gpa;
> > +	u16				vmid;
> > +	u16				reserved[3];
> > +	u32				regions_num;
> > +	u64				regions_gpa;
> > +	struct vm_memory_region_op	regions_op[];
> Please use Whitespace instead of Tab.

Sorry, but I don't understand. Do you prefer something like?:

diff --git a/drivers/virt/acrn/acrn_drv.h b/drivers/virt/acrn/acrn_drv.h
index fcc2e3e5232a..5663c17ad37c 100644
--- a/drivers/virt/acrn/acrn_drv.h
+++ b/drivers/virt/acrn/acrn_drv.h
@@ -56,11 +56,11 @@ struct vm_memory_region_op {
  * ACRN Hypervisor.
  */
 struct vm_memory_region_batch {
-	u16				vmid;
-	u16				reserved[3];
-	u32				regions_num;
-	u64				regions_gpa;
-	struct vm_memory_region_op	regions_op[];
+	u16			   vmid;
+	u16			   reserved[3];
+	u32			   regions_num;
+	u64			   regions_gpa;
+	struct vm_memory_region_op regions_op[];
 };

 /**

Moreover, for the v2 I will fix the typo "syze->size" in the subject as
suggested Kees ;)

Regards,
Len

Re: [PATCH] virt: acrn: Prefer array_syze and struct_size over open coded arithmetic

[Li Fei1]

On Fri, Oct 15, 2021 at 05:52:48PM +0200, Len Baker wrote:
> Hi Li,
> 
> On Tue, Oct 12, 2021 at 09:34:29AM +0800, Li Fei1 wrote:
> > On Mon, Oct 11, 2021 at 12:39:02PM +0200, Len Baker wrote:
> > > As noted in the "Deprecated Interfaces, Language Features, Attributes,
> > > and Conventions" documentation [1], size calculations (especially
> > > multiplication) should not be performed in memory allocator (or similar)
> > > function arguments due to the risk of them overflowing. This could lead
> > > to values wrapping around and a smaller allocation being made than the
> > > caller was expecting. Using those allocations could lead to linear
> > > overflows of heap memory and other misbehaviors.
> > >
> > > So, use the array_size() helper to do the arithmetic instead of the
> > > argument "count * size" in the vzalloc() function.
> > >
> > > Also, take the opportunity to add a flexible array member of struct
> > > vm_memory_region_op to the vm_memory_region_batch structure. And then,
> > > change the code accordingly and use the struct_size() helper to do the
> > > arithmetic instead of the argument "size + size * count" in the kzalloc
> > > function.
> > >
> > > This code was detected with the help of Coccinelle and audited and fixed
> > > manually.
> > >
> > > [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments
> > >
> > > Signed-off-by: Len Baker <len.baker@gmx.com>
> >
> > Hi Baker
> >
> > Thanks for helping us to fix this issue. This patch looks good to me.
> > Please add Signed-off-by: Fei Li <fei1.li@intel.com>.
> 
> I can't add the "Signed-off-by" tag by myself. However, if you are in the
> path to forward the patch to the mainline (maintainer's tree), you can
> add by yourself the "Signed-off-by" tag before send a "pull" to Linus.
> See [1] for more information.
> 
> [1] https://www.kernel.org/doc/html/latest/process/submitting-patches.html#sign-your-work-the-developer-s-certificate-of-origin
> 
> If you don't have a maintainer's tree, you can give (as a maintainer) an
> "Acked-by" tag that then I can add to the patch. More info in [2].

Acked-by: Fei Li <fei1.li@intel.com>

thanks.

> 
> [2] https://www.kernel.org/doc/html/latest/process/submitting-patches.html#when-to-use-acked-by-cc-and-co-developed-by
> 
> > Only two minor comments.
> >
> >
> > > ---
> > >  drivers/virt/acrn/acrn_drv.h | 10 ++++++----
> > >  drivers/virt/acrn/mm.c       |  9 ++++-----
> > >  2 files changed, 10 insertions(+), 9 deletions(-)
> > >
> > > diff --git a/drivers/virt/acrn/acrn_drv.h b/drivers/virt/acrn/acrn_drv.h
> > > index 1be54efa666c..fcc2e3e5232a 100644
> > > --- a/drivers/virt/acrn/acrn_drv.h
> > > +++ b/drivers/virt/acrn/acrn_drv.h
> > > @@ -48,6 +48,7 @@ struct vm_memory_region_op {
> > >   * @reserved:		Reserved.
> > >   * @regions_num:	The number of vm_memory_region_op.
> > >   * @regions_gpa:	Physical address of a vm_memory_region_op array.
> > > + * @regions_op:		Flexible array of vm_memory_region_op.
> > One Tab please.
> 
> Sorry, but if I use only one tab, the parameters description are not all
> aligned.
> 
> > >   *
> > >   * HC_VM_SET_MEMORY_REGIONS uses this structure to manage EPT mappings of
> > >   * multiple memory regions of a User VM. A &struct vm_memory_region_batch
> > > @@ -55,10 +56,11 @@ struct vm_memory_region_op {
> > >   * ACRN Hypervisor.
> > >   */
> > >  struct vm_memory_region_batch {
> > > -	u16	vmid;
> > > -	u16	reserved[3];
> > > -	u32	regions_num;
> > > -	u64	regions_gpa;
> > > +	u16				vmid;
> > > +	u16				reserved[3];
> > > +	u32				regions_num;
> > > +	u64				regions_gpa;
> > > +	struct vm_memory_region_op	regions_op[];
> > Please use Whitespace instead of Tab.
> 
> Sorry, but I don't understand. Do you prefer something like?:
> 
> diff --git a/drivers/virt/acrn/acrn_drv.h b/drivers/virt/acrn/acrn_drv.h
> index fcc2e3e5232a..5663c17ad37c 100644
> --- a/drivers/virt/acrn/acrn_drv.h
> +++ b/drivers/virt/acrn/acrn_drv.h
> @@ -56,11 +56,11 @@ struct vm_memory_region_op {
>   * ACRN Hypervisor.
>   */
>  struct vm_memory_region_batch {
> -	u16				vmid;
> -	u16				reserved[3];
> -	u32				regions_num;
> -	u64				regions_gpa;
> -	struct vm_memory_region_op	regions_op[];
> +	u16			   vmid;
> +	u16			   reserved[3];
> +	u32			   regions_num;
> +	u64			   regions_gpa;
> +	struct vm_memory_region_op regions_op[];
>  };
> 
>  /**
> 
> Moreover, for the v2 I will fix the typo "syze->size" in the subject as
> suggested Kees ;)
> 
> Regards,
> Len