[PATCH] crypto: s390/hmac - Fix counter in export state

[Herbert Xu <herbert@gondor.apana.org.au>]

On Fri, May 23, 2025 at 10:02:18AM +0200, Ingo Franzki wrote:
> 
> Yes, indeed, reverting this commit makes the problem to go away. 

Great.  While I've got your attenttion, could you also test this
patch to see if it makes the hmac errors go away?

Thanks,

---8<---
The hmac export state needs to be one block-size bigger to account
for the ipad.

Reported-by: Ingo Franzki <ifranzki@linux.ibm.com>
Fixes: 08811169ac01 ("crypto: s390/hmac - Use API partial block handling")
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/arch/s390/crypto/hmac_s390.c b/arch/s390/crypto/hmac_s390.c
index 93a1098d9f8d..58444da9b004 100644
--- a/arch/s390/crypto/hmac_s390.c
+++ b/arch/s390/crypto/hmac_s390.c
@@ -290,6 +290,7 @@ static int s390_hmac_export(struct shash_desc *desc, void *out)
 	struct s390_kmac_sha2_ctx *ctx = shash_desc_ctx(desc);
 	unsigned int bs = crypto_shash_blocksize(desc->tfm);
 	unsigned int ds = bs / 2;
+	u64 lo = ctx->buflen[0];
 	union {
 		u8 *u8;
 		u64 *u64;
@@ -301,9 +302,10 @@ static int s390_hmac_export(struct shash_desc *desc, void *out)
 	else
 		memcpy(p.u8, ctx->param, ds);
 	p.u8 += ds;
-	put_unaligned(ctx->buflen[0], p.u64++);
+	lo += bs;
+	put_unaligned(lo, p.u64++);
 	if (ds == SHA512_DIGEST_SIZE)
-		put_unaligned(ctx->buflen[1], p.u64);
+		put_unaligned(ctx->buflen[1] + (lo < bs), p.u64);
 	return err;
 }
 
@@ -316,14 +318,16 @@ static int s390_hmac_import(struct shash_desc *desc, const void *in)
 		const u8 *u8;
 		const u64 *u64;
 	} p = { .u8 = in };
+	u64 lo;
 	int err;
 
 	err = s390_hmac_sha2_init(desc);
 	memcpy(ctx->param, p.u8, ds);
 	p.u8 += ds;
-	ctx->buflen[0] = get_unaligned(p.u64++);
+	lo = get_unaligned(p.u64++);
+	ctx->buflen[0] = lo - bs;
 	if (ds == SHA512_DIGEST_SIZE)
-		ctx->buflen[1] = get_unaligned(p.u64);
+		ctx->buflen[1] = get_unaligned(p.u64) - (lo < bs);
 	if (ctx->buflen[0] | ctx->buflen[1])
 		ctx->gr0.ikp = 1;
 	return err;
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt