2023-06-27 15:03:22

by Julia Lawall

Subject: [PATCH v2 06/24] dma-buf: system_heap: use vmalloc_array and vcalloc

Use vmalloc_array and vcalloc to protect against
multiplication overflows.

The changes were done using the following Coccinelle
semantic patch:

// <smpl>
@initialize:ocaml@
@@

let rename alloc =
match alloc with
"vmalloc" -> "vmalloc_array"
| "vzalloc" -> "vcalloc"
| _ -> failwith "unknown"

@@
size_t e1,e2;
constant C1, C2;
expression E1, E2, COUNT, x1, x2, x3;
typedef u8;
typedef __u8;
type t = {u8,__u8,char,unsigned char};
identifier alloc = {vmalloc,vzalloc};
fresh identifier realloc = script:ocaml(alloc) { rename alloc };
@@

(
alloc(x1*x2*x3)
|
alloc(C1 * C2)
|
alloc((sizeof(t)) * (COUNT), ...)
|
- alloc((e1) * (e2))
+ realloc(e1, e2)
|
- alloc((e1) * (COUNT))
+ realloc(COUNT, e1)
|
- alloc((E1) * (E2))
+ realloc(E1, E2)
)
// </smpl>

Signed-off-by: Julia Lawall <[email protected]>

---
v2: Use vmalloc_array and vcalloc instead of array_size.
This also leaves a multiplication of a constant by a sizeof
as is. Two patches are thus dropped from the series.

drivers/dma-buf/heaps/system_heap.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff -u -p a/drivers/dma-buf/heaps/system_heap.c b/drivers/dma-buf/heaps/system_heap.c
--- a/drivers/dma-buf/heaps/system_heap.c
+++ b/drivers/dma-buf/heaps/system_heap.c
@@ -221,7 +221,7 @@ static void *system_heap_do_vmap(struct
{
struct sg_table *table = &buffer->sg_table;
int npages = PAGE_ALIGN(buffer->len) / PAGE_SIZE;
- struct page **pages = vmalloc(sizeof(struct page *) * npages);
+ struct page **pages = vmalloc_array(npages, sizeof(struct page *));
struct page **tmp = pages;
struct sg_page_iter piter;
void *vaddr;

2023-06-27 19:20:58

by John Stultz

Subject: Re: [PATCH v2 06/24] dma-buf: system_heap: use vmalloc_array and vcalloc

On Tue, Jun 27, 2023 at 7:44 AM Julia Lawall <[email protected]> wrote:
>
> Use vmalloc_array and vcalloc to protect against
> multiplication overflows.
>
> The changes were done using the following Coccinelle
> semantic patch:
>
> // <smpl>
> @initialize:ocaml@
> @@
>
> let rename alloc =
> match alloc with
> "vmalloc" -> "vmalloc_array"
> | "vzalloc" -> "vcalloc"
> | _ -> failwith "unknown"
>
> @@
> size_t e1,e2;
> constant C1, C2;
> expression E1, E2, COUNT, x1, x2, x3;
> typedef u8;
> typedef __u8;
> type t = {u8,__u8,char,unsigned char};
> identifier alloc = {vmalloc,vzalloc};
> fresh identifier realloc = script:ocaml(alloc) { rename alloc };
> @@
>
> (
> alloc(x1*x2*x3)
> |
> alloc(C1 * C2)
> |
> alloc((sizeof(t)) * (COUNT), ...)
> |
> - alloc((e1) * (e2))
> + realloc(e1, e2)
> |
> - alloc((e1) * (COUNT))
> + realloc(COUNT, e1)
> |
> - alloc((E1) * (E2))
> + realloc(E1, E2)
> )
> // </smpl>
>
> Signed-off-by: Julia Lawall <[email protected]>
>
> ---
> v2: Use vmalloc_array and vcalloc instead of array_size.
> This also leaves a multiplication of a constant by a sizeof
> as is. Two patches are thus dropped from the series.
>
> drivers/dma-buf/heaps/system_heap.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff -u -p a/drivers/dma-buf/heaps/system_heap.c b/drivers/dma-buf/heaps/system_heap.c
> --- a/drivers/dma-buf/heaps/system_heap.c
> +++ b/drivers/dma-buf/heaps/system_heap.c
> @@ -221,7 +221,7 @@ static void *system_heap_do_vmap(struct
> {
> struct sg_table *table = &buffer->sg_table;
> int npages = PAGE_ALIGN(buffer->len) / PAGE_SIZE;
> - struct page **pages = vmalloc(sizeof(struct page *) * npages);
> + struct page **pages = vmalloc_array(npages, sizeof(struct page *));
> struct page **tmp = pages;
> struct sg_page_iter piter;
> void *vaddr;

Seems reasonable. Thanks for sending this out!

Acked-by: John Stultz <[email protected]>

thanks
-john