[PATCH] scsi: elx: libefc: Prefer kcalloc over open coded arithmetic

[PATCH] scsi: elx: libefc: Prefer kcalloc 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 purpose specific kcalloc() function instead of the argument
count * size in the kzalloc() function.

[1] https://www.kernel.org/doc/html/v5.14/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments

Signed-off-by: Len Baker <len.baker@gmx.com>
---
 drivers/scsi/elx/libefc/efc_fabric.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/scsi/elx/libefc/efc_fabric.c b/drivers/scsi/elx/libefc/efc_fabric.c
index d397220d9e54..f9412437ad47 100644
--- a/drivers/scsi/elx/libefc/efc_fabric.c
+++ b/drivers/scsi/elx/libefc/efc_fabric.c
@@ -686,7 +686,7 @@ efc_process_gidpt_payload(struct efc_node *node,
 	}

 	/* Allocate a buffer for all nodes */
-	active_nodes = kzalloc(port_count * sizeof(*active_nodes), GFP_ATOMIC);
+	active_nodes = kcalloc(port_count, sizeof(*active_nodes), GFP_ATOMIC);
 	if (!active_nodes) {
 		node_printf(node, "efc_malloc failed\n");
 		return -EIO;
--
2.25.1

Re: [PATCH] scsi: elx: libefc: Prefer kcalloc over open coded arithmetic

[James Smart]

On 9/4/2021 11:24 PM, 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 purpose specific kcalloc() function instead of the argument
> count * size in the kzalloc() function.
> 
> [1] https://www.kernel.org/doc/html/v5.14/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments
> 
> Signed-off-by: Len Baker <len.baker@gmx.com>

Looks good.  Thanks

Reviewed-by: James Smart <jsmart2021@gmail.com>

-- james

Re: [PATCH] scsi: elx: libefc: Prefer kcalloc over open coded arithmetic

[Martin K. Petersen]

On Sun, 5 Sep 2021 08:24:48 +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.
> 
> [...]

Applied to 5.16/scsi-queue, thanks!

[1/1] scsi: elx: libefc: Prefer kcalloc over open coded arithmetic
      https://git.kernel.org/mkp/scsi/c/0a5e20fc8ca7

-- 
Martin K. Petersen	Oracle Linux Engineering