[PATCH 6.12,6.15] crypto: s390/sha - Fix uninitialized variable in SHA-1 and SHA-2

[PATCH 6.12,6.15] crypto: s390/sha - Fix uninitialized variable in SHA-1 and SHA-2

[Eric Biggers]

commit 68279380266a5fa70e664de754503338e2ec3f43 upstream.

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() (now s390_sha_update_blocks()).  At the time,
s390_sha_update() 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. the function code CPACF_KIMD_SHA_512 |
CPACF_KIMD_NIP to be used instead of just CPACF_KIMD_SHA_512.  This
apparently was harmless, as the SHA-1 and SHA-2 function codes ignore
CPACF_KIMD_NIP; it is recognized only by the SHA-3 function codes
(https://lore.kernel.org/r/73477fe9-a1dc-4e38-98a6-eba9921e8afa@linux.ibm.com/).
Therefore, this bug was found only when first_message_part was later
converted to a boolean and UBSAN detected its uninitialized use.
Regardless, let's fix this by just initializing to zero.

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@vger.kernel.org
Reported-by: Ingo Franzki <ifranzki@linux.ibm.com>
Closes: https://lore.kernel.org/r/12740696-595c-4604-873e-aefe8b405fbf@linux.ibm.com
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Link: https://lore.kernel.org/r/20250703172316.7914-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
---
 arch/s390/crypto/sha1_s390.c   | 2 ++
 arch/s390/crypto/sha256_s390.c | 3 +++
 arch/s390/crypto/sha512_s390.c | 3 +++
 3 files changed, 8 insertions(+)

diff --git a/arch/s390/crypto/sha1_s390.c b/arch/s390/crypto/sha1_s390.c
index bc3a22704e09..10950953429e 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 = 0;
 
 	return 0;
 }
 
 static int s390_sha1_export(struct shash_desc *desc, void *out)
@@ -60,10 +61,11 @@ static int s390_sha1_import(struct shash_desc *desc, const void *in)
 
 	sctx->count = ictx->count;
 	memcpy(sctx->state, ictx->state, sizeof(ictx->state));
 	memcpy(sctx->buf, ictx->buffer, sizeof(ictx->buffer));
 	sctx->func = CPACF_KIMD_SHA_1;
+	sctx->first_message_part = 0;
 	return 0;
 }
 
 static struct shash_alg alg = {
 	.digestsize	=	SHA1_DIGEST_SIZE,
diff --git a/arch/s390/crypto/sha256_s390.c b/arch/s390/crypto/sha256_s390.c
index 6f1ccdf93d3e..0204d4bca340 100644
--- a/arch/s390/crypto/sha256_s390.c
+++ b/arch/s390/crypto/sha256_s390.c
@@ -29,10 +29,11 @@ static int s390_sha256_init(struct shash_desc *desc)
 	sctx->state[5] = SHA256_H5;
 	sctx->state[6] = SHA256_H6;
 	sctx->state[7] = SHA256_H7;
 	sctx->count = 0;
 	sctx->func = CPACF_KIMD_SHA_256;
+	sctx->first_message_part = 0;
 
 	return 0;
 }
 
 static int sha256_export(struct shash_desc *desc, void *out)
@@ -53,10 +54,11 @@ static int sha256_import(struct shash_desc *desc, const void *in)
 
 	sctx->count = ictx->count;
 	memcpy(sctx->state, ictx->state, sizeof(ictx->state));
 	memcpy(sctx->buf, ictx->buf, sizeof(ictx->buf));
 	sctx->func = CPACF_KIMD_SHA_256;
+	sctx->first_message_part = 0;
 	return 0;
 }
 
 static struct shash_alg sha256_alg = {
 	.digestsize	=	SHA256_DIGEST_SIZE,
@@ -88,10 +90,11 @@ static int s390_sha224_init(struct shash_desc *desc)
 	sctx->state[5] = SHA224_H5;
 	sctx->state[6] = SHA224_H6;
 	sctx->state[7] = SHA224_H7;
 	sctx->count = 0;
 	sctx->func = CPACF_KIMD_SHA_256;
+	sctx->first_message_part = 0;
 
 	return 0;
 }
 
 static struct shash_alg sha224_alg = {
diff --git a/arch/s390/crypto/sha512_s390.c b/arch/s390/crypto/sha512_s390.c
index 04f11c407763..b53a7793bd24 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)
 	*(__u64 *)&ctx->state[10] = SHA512_H5;
 	*(__u64 *)&ctx->state[12] = SHA512_H6;
 	*(__u64 *)&ctx->state[14] = SHA512_H7;
 	ctx->count = 0;
 	ctx->func = CPACF_KIMD_SHA_512;
+	ctx->first_message_part = 0;
 
 	return 0;
 }
 
 static int sha512_export(struct shash_desc *desc, void *out)
@@ -58,10 +59,11 @@ static int sha512_import(struct shash_desc *desc, const void *in)
 	sctx->count = ictx->count[0];
 
 	memcpy(sctx->state, ictx->state, sizeof(ictx->state));
 	memcpy(sctx->buf, ictx->buf, sizeof(ictx->buf));
 	sctx->func = CPACF_KIMD_SHA_512;
+	sctx->first_message_part = 0;
 	return 0;
 }
 
 static struct shash_alg sha512_alg = {
 	.digestsize	=	SHA512_DIGEST_SIZE,
@@ -95,10 +97,11 @@ static int sha384_init(struct shash_desc *desc)
 	*(__u64 *)&ctx->state[10] = SHA384_H5;
 	*(__u64 *)&ctx->state[12] = SHA384_H6;
 	*(__u64 *)&ctx->state[14] = SHA384_H7;
 	ctx->count = 0;
 	ctx->func = CPACF_KIMD_SHA_512;
+	ctx->first_message_part = 0;
 
 	return 0;
 }
 
 static struct shash_alg sha384_alg = {

base-commit: 7b59ab988c01c190f1b528cf750d6f33b738d1e2
-- 
2.50.0.727.gbf7dc18ff4-goog