[PATCH v5 1/1] crypto: atmel-sha204a - fix blocking and non-blocking rng logic

[Herbert Xu]

On Sun, Apr 26, 2026 at 09:29:47PM +0000, Lothar Rubusch wrote:
> The blocking and non-blocking paths were failing to provide valid entropy
> due to improper buffer management. Reading the buffer starting from byte 1,
> only fetch the 32 bytes of random data from the return message.
> 
> Tested on an Atmel SHA204A device.
> 
> Before (here for blocking), tests showed repeatedly reading reduced bytes.
> $ head -c 32 /dev/hwrng | hexdump -C
> 00000000  02 28 85 b3 47 40 f2 ee  00 00 00 00 00 00 00 00  |.(..G at ..........|
> 00000010  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
> 00000020
> 
> After, the result will be similar to the following:
> $ head -c 32 /dev/hwrng | hexdump -C
> 00000000  5a fc 3f 13 14 68 fe 06  68 0a bd 04 83 6e 09 69  |Z.?..h..h....n.i|
> 00000010  75 ff cf 87 10 84 3b c9  c1 df ae eb 45 53 4c c3  |u.....;.....ESL.|
> 00000020
> 
> Fixes: da001fb651b0 ("crypto: atmel-i2c - add support for SHA204A random number generator")
> Suggested-by: Ard Biesheuvel <ardb at kernel.org>
> Signed-off-by: Lothar Rubusch <l.rubusch at gmail.com>
> ---
>  drivers/crypto/atmel-sha204a.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)

Patch applied.  Thanks.
-- 
Email: Herbert Xu <herbert at gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
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