[PATCH] ipw2x00: Use struct_size helper instead of open-coded arithmetic

[PATCH] ipw2x00: Use struct_size helper instead of open-coded arithmetic

[Len Baker]

Dynamic size calculations (especially multiplication) should not be
performed in memory allocator 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.

To avoid this scenario, use the struct_size helper.

Signed-off-by: Len Baker <len.baker@gmx.com>
---
 drivers/net/wireless/intel/ipw2x00/libipw_tx.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/intel/ipw2x00/libipw_tx.c b/drivers/net/wireless/intel/ipw2x00/libipw_tx.c
index d9baa2fa603b..36d1e6b2568d 100644
--- a/drivers/net/wireless/intel/ipw2x00/libipw_tx.c
+++ b/drivers/net/wireless/intel/ipw2x00/libipw_tx.c
@@ -179,8 +179,8 @@ static struct libipw_txb *libipw_alloc_txb(int nr_frags, int txb_size,
 {
 	struct libipw_txb *txb;
 	int i;
-	txb = kmalloc(sizeof(struct libipw_txb) + (sizeof(u8 *) * nr_frags),
-		      gfp_mask);
+
+	txb = kmalloc(struct_size(txb, fragments, nr_frags), gfp_mask);
 	if (!txb)
 		return NULL;

--
2.25.1

Re: [PATCH] ipw2x00: Use struct_size helper instead of open-coded arithmetic

[Stanislav Yakovlev]

On Sat, 17 Jul 2021 at 18:25, Len Baker <len.baker@gmx.com> wrote:
>
> Dynamic size calculations (especially multiplication) should not be
> performed in memory allocator 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.
>
> To avoid this scenario, use the struct_size helper.
>
> Signed-off-by: Len Baker <len.baker@gmx.com>
> ---
>  drivers/net/wireless/intel/ipw2x00/libipw_tx.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>

Looks fine, thanks!

Stanislav.

Re: [PATCH] ipw2x00: Use struct_size helper instead of open-coded arithmetic

[Kalle Valo]

Len Baker <len.baker@gmx.com> wrote:

> Dynamic size calculations (especially multiplication) should not be
> performed in memory allocator 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.
> 
> To avoid this scenario, use the struct_size helper.
> 
> Signed-off-by: Len Baker <len.baker@gmx.com>

Patch applied to wireless-drivers-next.git, thanks.

6f78f4a41ee0 ipw2x00: Use struct_size helper instead of open-coded arithmetic

-- 
https://patchwork.kernel.org/project/linux-wireless/patch/20210717142513.5411-1-len.baker@gmx.com/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches