s390/zcrypt: Validate length for CCA ECC private key requests

cca_ecc2protkey() derives the copy length for the CPRB parameter
block directly from the length field in the key token. Reject the
request early if the token length exceeds the available space in the
parameter block.

Fixes: fa6999e326fe ("s390/pkey: support CCA and EP11 secure ECC private keys")
Signed-off-by: Holger Dengler <dengler@linux.ibm.com>
Cc: stable@vger.kernel.org # 5.10+
Reviewed-by: Harald Freudenberger <freude@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

diff --git a/drivers/s390/crypto/zcrypt_ccamisc.c b/drivers/s390/crypto/zcrypt_ccamisc.c
index db6a421..322677a 100644 (file)
--- a/drivers/s390/crypto/zcrypt_ccamisc.c
+++ b/drivers/s390/crypto/zcrypt_ccamisc.c
@@ -1428,6 +1428,9 @@ int cca_ecc2protkey(u16 cardnr, u16 domain, const u8 *key,
        } __packed * prepparm;
        int keylen = ((struct eccprivkeytoken *)key)->len;
 
+       if (keylen > PARMBSIZE - sizeof(struct aureqparm))
+               return -EINVAL;
+
        /* get already prepared memory for 2 cprbs with param block each */
        rc = alloc_and_prep_cprbmem(PARMBSIZE, &mem,
                                    &preqcblk, &prepcblk, xflags);