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s390/zcrypt: Fix uninitialized padding in CRT key structure

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The zcrypt_type6_crt_key() function leaves padding bytes uninitialized
between key components and the modulus in the CCA CRT key token. These
padding bytes are sent to the crypto card, potentially leaking kernel
memory contents.

The initial memset() only zeros fixed structure fields, not the
flexible array member key_parts[] where the padding resides. While key
components are properly copied from userspace, the calculated pad_len
bytes between them remain uninitialized.

Fix by explicitly zeroing the padding bytes after copying the CRT key
components.

Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
Reviewed-by: Finn Callies <fcallies@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
This commit is contained in:
Harald Freudenberger 2026-08-25 18:01:54 +02:00 committed by Heiko Carstens
parent 33123ff9cb
commit 98d23edcd4
1 changed files with 1 additions and 0 deletions
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drivers/s390/crypto/zcrypt_cca_key.h
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@ -219,6 +219,7 @@ static inline int zcrypt_type6_crt_key(struct ica_rsa_modexpo_crt *crt, void *p)
copy_from_user(key->key_parts + 2 * long_len + 2 * short_len,
crt->u_mult_inv, long_len))
return -EFAULT;
memset(key->key_parts + 3 * long_len + 2 * short_len, 0, pad_len);
memset(key->key_parts + 3 * long_len + 2 * short_len + pad_len,
0xff, crt->inputdatalength);
pub = (struct cca_public_sec *)(key->key_parts + key_len);