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s390/crypto: Fix missing scrub of temp buffers with AES ctr and gcm algorithm

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In function ctr_aes_crypt() there is a buffer used to process
remaining bytes < AES_BLOCK_SIZE. This buffer was not scrubbed and
thus could lead to expose of unwanted data. When the buffer is used
explicitly scrub it at the end of the code block to avoid exposure of
maybe sensitive data.

In a similar way the function gcm_aes_crypt() hat an error path where
the CPACF param block was not scrubbed. Instead of return early now
these error paths go to end of function where explicit scrubbing is
done. Similar with the buffers which are part of the gcm_sg_walk
structs from the variables gw_in and gw_out.

Fixes: d07f951903 ("crypto: s390/aes - Fix buffer overread in CTR mode")
Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
Reviewed-by: Holger Dengler <dengler@linux.ibm.com>
Cc: stable@vger.kernel.org # 6.8+
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
This commit is contained in:
Harald Freudenberger 2026-08-31 10:37:34 +02:00 committed by Vasily Gorbik
parent 15fa028589
commit 8b7c3b6914
1 changed files with 12 additions and 4 deletions
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16
arch/s390/crypto/aes_s390.c
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@ -604,6 +604,7 @@ static int ctr_aes_crypt(struct skcipher_request *req)
memcpy(walk.dst.virt.addr, buf, nbytes);
crypto_inc(walk.iv, AES_BLOCK_SIZE);
ret = skcipher_walk_done(&walk, 0);
memzero_explicit(buf, sizeof(buf));
}
return ret;
@ -895,10 +896,14 @@ static int gcm_aes_crypt(struct aead_request *req, unsigned int flags)
gw_in.ptr, aad_bytes);
n = aad_bytes + pc_bytes;
if (gcm_in_walk_done(&gw_in, n) != n)
return -ENOMEM;
if (gcm_out_walk_done(&gw_out, n) != n)
return -ENOMEM;
if (gcm_in_walk_done(&gw_in, n) != n) {
ret = -ENOMEM;
goto out;
}
if (gcm_out_walk_done(&gw_out, n) != n) {
ret = -ENOMEM;
goto out;
}
aadlen -= aad_bytes;
pclen -= pc_bytes;
} while (aadlen + pclen > 0);
@ -910,7 +915,10 @@ static int gcm_aes_crypt(struct aead_request *req, unsigned int flags)
} else
scatterwalk_map_and_copy(param.t, req->dst, len, taglen, 1);
out:
memzero_explicit(&param, sizeof(param));
memzero_explicit(gw_in.buf, sizeof(gw_in.buf));
memzero_explicit(gw_out.buf, sizeof(gw_out.buf));
return ret;
}