Re: [PATCH v6 2/2] s390/zcrypt: Improve EP11 CPRB length and overflow checks

[sashiko-bot@kernel.org]

> The xcrb_msg_to_type6_ep11cprb_msgx() function lacks proper input
> validation, creating security vulnerabilities:
> 1. Missing minimum size validation: The ep11_cprb structure and
>    subsequent payload fields (pld_tag, pld_lenfmt) are copied from
>    userspace without verifying sufficient buffer length.
> 2. Arithmetic overflow in length calculations: CEIL4 alignment could
>    overflow, bypassing size checks and enabling buffer overflows.
> 3. There was a gap between the message size copied from user space and
>    the message buffer sent down to the card. The msg buffer size is
>    rounded up to 4 byte boundary.
> 
> Fix by using size_t for length calculations, adding U32_MAX boundary
> checks after alignment, and validating minimum request size and
> minimum reply size before copying from userspace. Also pad the gap
> between user space copied message and message buffer sent down to the
> card by zeros.
> 
> Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>

Sashiko has reviewed this patch and found no issues. It looks great!

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Sashiko AI review · https://sashiko.dev/#/patchset/20260727083200.151976-1-freude@linux.ibm.com?part=2