Re: [PATCH v11 4/5] s390/zcrypt: Improve EP11 CPRB domain handling with ASN.1 parsing

[sashiko-bot@kernel.org]

> The zcrypt_msgtype6_send_ep11_cprb() function uses fragile struct
> overlays to access and modify the domain field in the EP11 CPRB
> payload, creating maintainability and security concerns:
> 1. Struct overlay approach (pld_hdr) assumes fixed payload structure
>    and doesn't validate the actual ASN.1 encoding.
> 2. Complex length format detection logic is error-prone and doesn't
>    properly validate bounds at each parsing step.
> 3. Direct struct member access bypasses proper ASN.1 validation.
> 
> Fix by replacing struct overlays with explicit ASN.1 parsing that
> validates each field (payload tag/length, function tag/length/value,
> optional domain tag/length/value) with proper bounds checking at every
> step. Add asn1_int_encode() helper function to safely write integer
> values with correct endianness conversion. This makes the code
> consistent with the validation pattern introduced with the rework of
> the xcrb_msg_to_type6_ep11cprb_msgx() function.
> 
> Fixes: e2c6d91eb8b1 ("s390/zcrypt: Rework domain processing within zcrypt device driver")
> 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/20260803083339.212885-1-freude@linux.ibm.com?part=4