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* [PATCH] i3c/master/mipi-i3c-hci: Prefer kcalloc over open coded arithmetic
@ 2021-09-12 15:51 Len Baker
  2021-09-13  1:54 ` Nicolas Pitre
  2021-09-13 17:39 ` Alexandre Belloni
  0 siblings, 2 replies; 3+ messages in thread
From: Len Baker @ 2021-09-12 15:51 UTC (permalink / raw)
  To: Alexandre Belloni
  Cc: Len Baker, Nicolas Pitre, Boris Brezillon, Kees Cook, linux-i3c,
	linux-hardening, linux-kernel

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
size * count 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/i3c/master/mipi-i3c-hci/hci.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/i3c/master/mipi-i3c-hci/hci.h b/drivers/i3c/master/mipi-i3c-hci/hci.h
index 80beb1d5be8f..f109923f6c3f 100644
--- a/drivers/i3c/master/mipi-i3c-hci/hci.h
+++ b/drivers/i3c/master/mipi-i3c-hci/hci.h
@@ -98,7 +98,7 @@ struct hci_xfer {

 static inline struct hci_xfer *hci_alloc_xfer(unsigned int n)
 {
-	return kzalloc(sizeof(struct hci_xfer) * n, GFP_KERNEL);
+	return kcalloc(n, sizeof(struct hci_xfer), GFP_KERNEL);
 }

 static inline void hci_free_xfer(struct hci_xfer *xfer, unsigned int n)
--
2.25.1


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^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [PATCH] i3c/master/mipi-i3c-hci: Prefer kcalloc over open coded arithmetic
  2021-09-12 15:51 [PATCH] i3c/master/mipi-i3c-hci: Prefer kcalloc over open coded arithmetic Len Baker
@ 2021-09-13  1:54 ` Nicolas Pitre
  2021-09-13 17:39 ` Alexandre Belloni
  1 sibling, 0 replies; 3+ messages in thread
From: Nicolas Pitre @ 2021-09-13  1:54 UTC (permalink / raw)
  To: Len Baker
  Cc: Alexandre Belloni, Boris Brezillon, Kees Cook, linux-i3c,
	linux-hardening, linux-kernel

On Sun, 12 Sep 2021, 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
> size * count 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>

Acked-by: Nicolas Pitre <npitre@baylibre.com>

> ---
>  drivers/i3c/master/mipi-i3c-hci/hci.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/i3c/master/mipi-i3c-hci/hci.h b/drivers/i3c/master/mipi-i3c-hci/hci.h
> index 80beb1d5be8f..f109923f6c3f 100644
> --- a/drivers/i3c/master/mipi-i3c-hci/hci.h
> +++ b/drivers/i3c/master/mipi-i3c-hci/hci.h
> @@ -98,7 +98,7 @@ struct hci_xfer {
> 
>  static inline struct hci_xfer *hci_alloc_xfer(unsigned int n)
>  {
> -	return kzalloc(sizeof(struct hci_xfer) * n, GFP_KERNEL);
> +	return kcalloc(n, sizeof(struct hci_xfer), GFP_KERNEL);
>  }
> 
>  static inline void hci_free_xfer(struct hci_xfer *xfer, unsigned int n)
> --
> 2.25.1
> 
> 

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^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [PATCH] i3c/master/mipi-i3c-hci: Prefer kcalloc over open coded arithmetic
  2021-09-12 15:51 [PATCH] i3c/master/mipi-i3c-hci: Prefer kcalloc over open coded arithmetic Len Baker
  2021-09-13  1:54 ` Nicolas Pitre
@ 2021-09-13 17:39 ` Alexandre Belloni
  1 sibling, 0 replies; 3+ messages in thread
From: Alexandre Belloni @ 2021-09-13 17:39 UTC (permalink / raw)
  To: Len Baker
  Cc: Alexandre Belloni, linux-kernel, Kees Cook, linux-i3c,
	linux-hardening, Nicolas Pitre, Boris Brezillon

On Sun, 12 Sep 2021 17:51:35 +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, thanks!

[1/1] i3c/master/mipi-i3c-hci: Prefer kcalloc over open coded arithmetic
      commit: 41a0430dd5ca65afdecf10fb0b8b56966a1c5d04

Best regards,
-- 
Alexandre Belloni <alexandre.belloni@bootlin.com>

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^ permalink raw reply	[flat|nested] 3+ messages in thread

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2021-09-12 15:51 [PATCH] i3c/master/mipi-i3c-hci: Prefer kcalloc over open coded arithmetic Len Baker
2021-09-13  1:54 ` Nicolas Pitre
2021-09-13 17:39 ` Alexandre Belloni

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