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crypto: drbg - Fix misaligned writes in CTR_DRBG and HASH_DRBG

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drbg_cpu_to_be32() is being used to do a plain write to a byte array,
which doesn't have any alignment guarantee.  This can cause a misaligned
write.  Replace it with the correct function, put_unaligned_be32().

Fixes: 72f3e00dd6 ("crypto: drbg - replace int2byte with cpu_to_be")
Cc: stable@vger.kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Eric Biggers
2026-04-19 23:33:46 -07:00
committed by Herbert Xu
parent 39a31ad9e2
commit ddc4dedb9b
3 changed files with 6 additions and 22 deletions
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7
crypto/df_sp80090a.c
View File

@@ -10,6 +10,7 @@
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/string.h>
#include <linux/unaligned.h>
#include <crypto/aes.h>
#include <crypto/df_sp80090a.h>
#include <crypto/internal/drbg.h>
@@ -141,10 +142,10 @@ int crypto_drbg_ctr_df(struct aes_enckey *aeskey,
/* 10.4.2 step 2 -- calculate the entire length of all input data */
list_for_each_entry(seed, seedlist, list)
inputlen += seed->len;
drbg_cpu_to_be32(inputlen, &L_N[0]);
put_unaligned_be32(inputlen, &L_N[0]);
/* 10.4.2 step 3 */
drbg_cpu_to_be32(bytes_to_return, &L_N[4]);
put_unaligned_be32(bytes_to_return, &L_N[4]);
/* 10.4.2 step 5: length is L_N, input_string, one byte, padding */
padlen = (inputlen + sizeof(L_N) + 1) % (blocklen_bytes);
@@ -175,7 +176,7 @@ int crypto_drbg_ctr_df(struct aes_enckey *aeskey,
* holds zeros after allocation -- even the increment of i
* is irrelevant as the increment remains within length of i
*/
drbg_cpu_to_be32(i, iv);
put_unaligned_be32(i, iv);
/* 10.4.2 step 9.2 -- BCC and concatenation with temp */
drbg_ctr_bcc(aeskey, temp + templen, K, &bcc_list,
blocklen_bytes, keylen);

3
crypto/drbg.c
View File

@@ -103,6 +103,7 @@
#include <linux/kernel.h>
#include <linux/jiffies.h>
#include <linux/string_choices.h>
#include <linux/unaligned.h>
/***************************************************************
* Backend cipher definitions available to DRBG
@@ -601,7 +602,7 @@ static int drbg_hash_df(struct drbg_state *drbg,
/* 10.4.1 step 3 */
input[0] = 1;
drbg_cpu_to_be32((outlen * 8), &input[1]);
put_unaligned_be32(outlen * 8, &input[1]);
/* 10.4.1 step 4.1 -- concatenation of data for input into hash */
drbg_string_fill(&data, input, 5);

18
include/crypto/internal/drbg.h
View File

@@ -9,24 +9,6 @@
#ifndef _INTERNAL_DRBG_H
#define _INTERNAL_DRBG_H
/*
* Convert an integer into a byte representation of this integer.
* The byte representation is big-endian
*
* @val value to be converted
* @buf buffer holding the converted integer -- caller must ensure that
* buffer size is at least 32 bit
*/
static inline void drbg_cpu_to_be32(__u32 val, unsigned char *buf)
{
struct s {
__be32 conv;
};
struct s *conversion = (struct s *)buf;
conversion->conv = cpu_to_be32(val);
}
/*
* Concatenation Helper and string operation helper
*