linux-kernel - [PATCH] crypto: s390/sha - Fix uninitialized variable in SHA-1 and SHA-2

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Message-ID: <20250627185649.35321-1-ebiggers@kernel.org>
Date: Fri, 27 Jun 2025 11:56:49 -0700
From: Eric Biggers <ebiggers@...nel.org>
To: linux-crypto@...r.kernel.org
Cc: linux-s390@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Harald Freudenberger <freude@...ux.ibm.com>,
	Holger Dengler <dengler@...ux.ibm.com>,
	Herbert Xu <herbert@...dor.apana.org.au>,
	Heiko Carstens <hca@...ux.ibm.com>,
	Vasily Gorbik <gor@...ux.ibm.com>,
	Alexander Gordeev <agordeev@...ux.ibm.com>,
	Christian Borntraeger <borntraeger@...ux.ibm.com>,
	Sven Schnelle <svens@...ux.ibm.com>,
	Joerg Schmidbauer <jschmidb@...ibm.com>,
	Ard Biesheuvel <ardb@...nel.org>,
	"Jason A . Donenfeld" <Jason@...c4.com>,
	Eric Biggers <ebiggers@...nel.org>,
	stable@...r.kernel.org,
	Ingo Franzki <ifranzki@...ux.ibm.com>
Subject: [PATCH] crypto: s390/sha - Fix uninitialized variable in SHA-1 and SHA-2

Commit 88c02b3f79a6 ("s390/sha3: Support sha3 performance enhancements")
added the field s390_sha_ctx::first_message_part and made it be used by
s390_sha_update_blocks().  At the time, s390_sha_update_blocks() was
used by all the s390 SHA-1, SHA-2, and SHA-3 algorithms.  However, only
the initialization functions for SHA-3 were updated, leaving SHA-1 and
SHA-2 using first_message_part uninitialized.

This could cause e.g. CPACF_KIMD_SHA_512 | CPACF_KIMD_NIP to be used
instead of just CPACF_KIMD_NIP.  It's unclear why this didn't cause a
problem earlier; this bug was found only when UBSAN detected the
uninitialized boolean.  Perhaps the CPU ignores CPACF_KIMD_NIP for SHA-1
and SHA-2.  Regardless, let's fix this.  For now just initialize to
false, i.e. don't try to "optimize" the SHA state initialization.

Note: in 6.16, we need to patch SHA-1, SHA-384, and SHA-512.  In 6.15
and earlier, we'll also need to patch SHA-224 and SHA-256, as they
hadn't yet been librarified (which incidentally fixed this bug).

Fixes: 88c02b3f79a6 ("s390/sha3: Support sha3 performance enhancements")
Cc: stable@...r.kernel.org
Reported-by: Ingo Franzki <ifranzki@...ux.ibm.com>
Closes: https://lore.kernel.org/r/12740696-595c-4604-873e-aefe8b405fbf@linux.ibm.com
Signed-off-by: Eric Biggers <ebiggers@...nel.org>
---

This is targeting 6.16.  I'd prefer to take this through
libcrypto-fixes, since the librarification work is also touching this
area.  But let me know if there's a preference for the crypto tree or
the s390 tree instead.

 arch/s390/crypto/sha1_s390.c   | 1 +
 arch/s390/crypto/sha512_s390.c | 2 ++
 2 files changed, 3 insertions(+)

diff --git a/arch/s390/crypto/sha1_s390.c b/arch/s390/crypto/sha1_s390.c
index d229cbd2ba229..73672e76a88f9 100644
--- a/arch/s390/crypto/sha1_s390.c
+++ b/arch/s390/crypto/sha1_s390.c
@@ -36,10 +36,11 @@ static int s390_sha1_init(struct shash_desc *desc)
 	sctx->state[2] = SHA1_H2;
 	sctx->state[3] = SHA1_H3;
 	sctx->state[4] = SHA1_H4;
 	sctx->count = 0;
 	sctx->func = CPACF_KIMD_SHA_1;
+	sctx->first_message_part = false;

 	return 0;
 }

 static int s390_sha1_export(struct shash_desc *desc, void *out)
diff --git a/arch/s390/crypto/sha512_s390.c b/arch/s390/crypto/sha512_s390.c
index 33711a29618c3..e9e112025ff22 100644
--- a/arch/s390/crypto/sha512_s390.c
+++ b/arch/s390/crypto/sha512_s390.c
@@ -30,10 +30,11 @@ static int sha512_init(struct shash_desc *desc)
 	ctx->sha512.state[6] = SHA512_H6;
 	ctx->sha512.state[7] = SHA512_H7;
 	ctx->count = 0;
 	ctx->sha512.count_hi = 0;
 	ctx->func = CPACF_KIMD_SHA_512;
+	ctx->first_message_part = false;

 	return 0;
 }

 static int sha512_export(struct shash_desc *desc, void *out)
@@ -95,10 +96,11 @@ static int sha384_init(struct shash_desc *desc)
 	ctx->sha512.state[6] = SHA384_H6;
 	ctx->sha512.state[7] = SHA384_H7;
 	ctx->count = 0;
 	ctx->sha512.count_hi = 0;
 	ctx->func = CPACF_KIMD_SHA_512;
+	ctx->first_message_part = false;

 	return 0;
 }

 static struct shash_alg sha384_alg = {

base-commit: e540341508ce2f6e27810106253d5de194b66750
-- 
2.50.0