s390/zcrypt: Improve EP11 CPRB length and overflow checks

Browse source

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. The payload is asn1 encoded but the function just uses a simple c
   struct overlay to access some fields of the payload.

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. Do a very simple
asn1 parsing of the payload up to the function value field.

Fixes: e2c6d91eb8 ("s390/zcrypt: Rework domain processing within zcrypt device driver")
Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
Cc: stable@vger.kernel.org # 7.1+
Reviewed-by: Holger Dengler <dengler@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

...

This commit is contained in:

Harald Freudenberger 2026-08-03 10:33:36 +02:00 • committed by Vasily Gorbik

parent 35ac6754ba

commit 17ac0bc866

1 changed files with 113 additions and 39 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

152

drivers/s390/crypto/zcrypt_msgtype6.c

View file