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Subject[PATCH 20/23] KEYS: DH: ensure the KDF counter is properly aligned
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Date
From: Eric Biggers <ebiggers@google.com>

Accessing a 'u8[4]' through a '__be32 *' violates alignment rules. Just
make the counter a __be32 instead.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Stephan Mueller <smueller@chronox.de>
---

security/keys/dh.c | 16 +++-------------
1 file changed, 3 insertions(+), 13 deletions(-)

diff --git a/security/keys/dh.c b/security/keys/dh.c
index 1c1cac677041..63ac87d430db 100644
--- a/security/keys/dh.c
+++ b/security/keys/dh.c
@@ -130,14 +130,6 @@ static void kdf_dealloc(struct kdf_sdesc *sdesc)
kzfree(sdesc);
}

-/* convert 32 bit integer into its string representation */
-static inline void crypto_kw_cpu_to_be32(u32 val, u8 *buf)
-{
- __be32 *a = (__be32 *)buf;
-
- *a = cpu_to_be32(val);
-}
-
/*
* Implementation of the KDF in counter mode according to SP800-108 section 5.1
* as well as SP800-56A section 5.8.1 (Single-step KDF).
@@ -154,16 +146,14 @@ static int kdf_ctr(struct kdf_sdesc *sdesc, const u8 *src, unsigned int slen,
unsigned int h = crypto_shash_digestsize(desc->tfm);
int err = 0;
u8 *dst_orig = dst;
- u32 i = 1;
- u8 iteration[sizeof(u32)];
+ __be32 counter = cpu_to_be32(1);

while (dlen) {
err = crypto_shash_init(desc);
if (err)
goto err;

- crypto_kw_cpu_to_be32(i, iteration);
- err = crypto_shash_update(desc, iteration, sizeof(u32));
+ err = crypto_shash_update(desc, (u8 *)&counter, sizeof(__be32));
if (err)
goto err;

@@ -189,7 +179,7 @@ static int kdf_ctr(struct kdf_sdesc *sdesc, const u8 *src, unsigned int slen,

dlen -= h;
dst += h;
- i++;
+ counter = cpu_to_be32(be32_to_cpu(counter) + 1);
}
}

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