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* [PATCH v2] nvmem: meson-mx-efuse: allow reading data smaller than word_size
@ 2019-07-27 19:34 Martin Blumenstingl
  2019-07-29 13:04 ` Neil Armstrong
  2019-08-06 10:03 ` Srinivas Kandagatla
  0 siblings, 2 replies; 3+ messages in thread
From: Martin Blumenstingl @ 2019-07-27 19:34 UTC (permalink / raw)
  To: linux-amlogic, srinivas.kandagatla
  Cc: Martin Blumenstingl, linux-kernel, linux-arm-kernel

Some Amlogic boards store the Ethernet MAC address inside the eFuse. The
Ethernet MAC address uses 6 bytes. The existing logic in
meson_mx_efuse_read() would write beyond the end of the data buffer when
trying to read data with a size that is not aligned to word_size (4
bytes on Meson8, Meson8b and Meson8m2).

Calculate the remaining data to copy inside meson_mx_efuse_read() so
reading 6 bytes doesn't write beyond the end of the data buffer.

Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
---
Changes since v1:
- switch from min() to min_t() to get rid of a compiler warning


 drivers/nvmem/meson-mx-efuse.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/nvmem/meson-mx-efuse.c b/drivers/nvmem/meson-mx-efuse.c
index 2976aef87c82..e8fc0baa09e7 100644
--- a/drivers/nvmem/meson-mx-efuse.c
+++ b/drivers/nvmem/meson-mx-efuse.c
@@ -155,7 +155,8 @@ static int meson_mx_efuse_read(void *context, unsigned int offset,
 		if (err)
 			break;
 
-		memcpy(buf + i, &tmp, efuse->config.word_size);
+		memcpy(buf + i, &tmp,
+		       min_t(size_t, bytes - i, efuse->config.word_size));
 	}
 
 	meson_mx_efuse_mask_bits(efuse, MESON_MX_EFUSE_CNTL1,
-- 
2.22.0


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

* Re: [PATCH v2] nvmem: meson-mx-efuse: allow reading data smaller than word_size
  2019-07-27 19:34 [PATCH v2] nvmem: meson-mx-efuse: allow reading data smaller than word_size Martin Blumenstingl
@ 2019-07-29 13:04 ` Neil Armstrong
  2019-08-06 10:03 ` Srinivas Kandagatla
  1 sibling, 0 replies; 3+ messages in thread
From: Neil Armstrong @ 2019-07-29 13:04 UTC (permalink / raw)
  To: Martin Blumenstingl, linux-amlogic, srinivas.kandagatla
  Cc: linux-kernel, linux-arm-kernel

On 27/07/2019 21:34, Martin Blumenstingl wrote:
> Some Amlogic boards store the Ethernet MAC address inside the eFuse. The
> Ethernet MAC address uses 6 bytes. The existing logic in
> meson_mx_efuse_read() would write beyond the end of the data buffer when
> trying to read data with a size that is not aligned to word_size (4
> bytes on Meson8, Meson8b and Meson8m2).
> 
> Calculate the remaining data to copy inside meson_mx_efuse_read() so
> reading 6 bytes doesn't write beyond the end of the data buffer.
> 
> Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
> ---
> Changes since v1:
> - switch from min() to min_t() to get rid of a compiler warning
> 
> 
>  drivers/nvmem/meson-mx-efuse.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/nvmem/meson-mx-efuse.c b/drivers/nvmem/meson-mx-efuse.c
> index 2976aef87c82..e8fc0baa09e7 100644
> --- a/drivers/nvmem/meson-mx-efuse.c
> +++ b/drivers/nvmem/meson-mx-efuse.c
> @@ -155,7 +155,8 @@ static int meson_mx_efuse_read(void *context, unsigned int offset,
>  		if (err)
>  			break;
>  
> -		memcpy(buf + i, &tmp, efuse->config.word_size);
> +		memcpy(buf + i, &tmp,
> +		       min_t(size_t, bytes - i, efuse->config.word_size));
>  	}
>  
>  	meson_mx_efuse_mask_bits(efuse, MESON_MX_EFUSE_CNTL1,
> 

Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>

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

* Re: [PATCH v2] nvmem: meson-mx-efuse: allow reading data smaller than word_size
  2019-07-27 19:34 [PATCH v2] nvmem: meson-mx-efuse: allow reading data smaller than word_size Martin Blumenstingl
  2019-07-29 13:04 ` Neil Armstrong
@ 2019-08-06 10:03 ` Srinivas Kandagatla
  1 sibling, 0 replies; 3+ messages in thread
From: Srinivas Kandagatla @ 2019-08-06 10:03 UTC (permalink / raw)
  To: Martin Blumenstingl, linux-amlogic; +Cc: linux-kernel, linux-arm-kernel



On 27/07/2019 20:34, Martin Blumenstingl wrote:
> Some Amlogic boards store the Ethernet MAC address inside the eFuse. The
> Ethernet MAC address uses 6 bytes. The existing logic in
> meson_mx_efuse_read() would write beyond the end of the data buffer when
> trying to read data with a size that is not aligned to word_size (4
> bytes on Meson8, Meson8b and Meson8m2).
> 
> Calculate the remaining data to copy inside meson_mx_efuse_read() so
> reading 6 bytes doesn't write beyond the end of the data buffer.
> 
> Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
> ---

Applied Thanks,
Srini

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linux-amlogic mailing list
linux-amlogic@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-amlogic

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

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2019-07-27 19:34 [PATCH v2] nvmem: meson-mx-efuse: allow reading data smaller than word_size Martin Blumenstingl
2019-07-29 13:04 ` Neil Armstrong
2019-08-06 10:03 ` Srinivas Kandagatla

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