comedi: Replace kcalloc + copy_from_user with memdup_array_user

[PATCH] comedi: Replace kcalloc + copy_from_user with memdup_array_user

Posted by Thorsten Blum 2 weeks ago

Replace kcalloc() followed by copy_from_user() with memdup_array_user()
to improve and simplify comedi_unlocked_ioctl().

No functional changes intended.

Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
---
 drivers/comedi/comedi_fops.c | 13 ++++---------
 1 file changed, 4 insertions(+), 9 deletions(-)

diff --git a/drivers/comedi/comedi_fops.c b/drivers/comedi/comedi_fops.c
index 7e2f2b1a1c36..dea698e509b1 100644
--- a/drivers/comedi/comedi_fops.c
+++ b/drivers/comedi/comedi_fops.c
@@ -2284,15 +2284,10 @@ static long comedi_unlocked_ioctl(struct file *file, unsigned int cmd,
 		rc = check_insnlist_len(dev, insnlist.n_insns);
 		if (rc)
 			break;
-		insns = kcalloc(insnlist.n_insns, sizeof(*insns), GFP_KERNEL);
-		if (!insns) {
-			rc = -ENOMEM;
-			break;
-		}
-		if (copy_from_user(insns, insnlist.insns,
-				   sizeof(*insns) * insnlist.n_insns)) {
-			rc = -EFAULT;
-			kfree(insns);
+		insns = memdup_array_user(insnlist.insns, insnlist.n_insns,
+					  sizeof(*insns));
+		if (IS_ERR(insns)) {
+			rc = PTR_ERR(insns);
 			break;
 		}
 		rc = do_insnlist_ioctl(dev, insns, insnlist.n_insns, file);
-- 
2.51.0

Re: [PATCH] comedi: Replace kcalloc + copy_from_user with memdup_array_user

Posted by Ian Abbott 2 weeks ago

On 17/09/2025 14:13, Thorsten Blum wrote:
> Replace kcalloc() followed by copy_from_user() with memdup_array_user()
> to improve and simplify comedi_unlocked_ioctl().
> 
> No functional changes intended.
> 
> Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
> ---
>   drivers/comedi/comedi_fops.c | 13 ++++---------
>   1 file changed, 4 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/comedi/comedi_fops.c b/drivers/comedi/comedi_fops.c
> index 7e2f2b1a1c36..dea698e509b1 100644
> --- a/drivers/comedi/comedi_fops.c
> +++ b/drivers/comedi/comedi_fops.c
> @@ -2284,15 +2284,10 @@ static long comedi_unlocked_ioctl(struct file *file, unsigned int cmd,
>   		rc = check_insnlist_len(dev, insnlist.n_insns);
>   		if (rc)
>   			break;
> -		insns = kcalloc(insnlist.n_insns, sizeof(*insns), GFP_KERNEL);
> -		if (!insns) {
> -			rc = -ENOMEM;
> -			break;
> -		}
> -		if (copy_from_user(insns, insnlist.insns,
> -				   sizeof(*insns) * insnlist.n_insns)) {
> -			rc = -EFAULT;
> -			kfree(insns);
> +		insns = memdup_array_user(insnlist.insns, insnlist.n_insns,
> +					  sizeof(*insns));
> +		if (IS_ERR(insns)) {
> +			rc = PTR_ERR(insns);
>   			break;
>   		}
>   		rc = do_insnlist_ioctl(dev, insns, insnlist.n_insns, file);

Looks good to me.  Thanks!

Reviewed-by: Ian Abbott <abbotti@mev.co.uk>

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