[PATCH 5.14 052/334] crypto: ecc - handle unaligned input buffer in ecc_swap_digits

Greg Kroah-Hartman
2021-09-13T14:25:57Z

From: Mian Yousaf Kaukab <ykaukab@suse.de>

[ Upstream commit 0469dede0eeeefe12a9a2fd76078f4a266513457 ]

ecdsa_set_pub_key() makes an u64 pointer at 1 byte offset of the key.
This results in an unaligned u64 pointer. This pointer is passed to
ecc_swap_digits() which assumes natural alignment.

This causes a kernel crash on an armv7 platform:
[ 0.409022] Unhandled fault: alignment exception (0x001) at 0xc2a0a6a9
...
[ 0.416982] PC is at ecdsa_set_pub_key+0xdc/0x120
...
[ 0.491492] Backtrace:
[ 0.492059] [<c07c266c>] (ecdsa_set_pub_key) from [<c07c75d4>] (test_akcipher_one+0xf4/0x6c0)

Handle unaligned input buffer in ecc_swap_digits() by replacing
be64_to_cpu() to get_unaligned_be64(). Change type of in pointer to
void to reflect it doesn’t necessarily need to be aligned.

Fixes: 4e6602916bc6 ("crypto: ecdsa - Add support for ECDSA signature verification")
Reported-by: Guillaume Gardet <guillaume.gardet@arm.com>
Suggested-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Mian Yousaf Kaukab <ykaukab@suse.de>
Tested-by: Stefan Berger <stefanb@linux.ibm.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
crypto/ecc.h | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/crypto/ecc.h b/crypto/ecc.h
index a006132646a4..1350e8eb6ac2 100644
--- a/crypto/ecc.h
+++ b/crypto/ecc.h
@@ -27,6 +27,7 @@
#define _CRYPTO_ECC_H

#include <crypto/ecc_curve.h>
+#include <asm/unaligned.h>

/* One digit is u64 qword. */
#define ECC_CURVE_NIST_P192_DIGITS 3
@@ -46,13 +47,13 @@
* @out: Output array
* @ndigits: Number of digits to copy
*/
-static inline void ecc_swap_digits(const u64 *in, u64 *out, unsigned int ndigits)
+static inline void ecc_swap_digits(const void *in, u64 *out, unsigned int ndigits)
{
const __be64 *src = (__force __be64 *)in;
int i;

for (i = 0; i < ndigits; i++)
- out[i] = be64_to_cpu(src[ndigits - 1 - i]);
+ out[i] = get_unaligned_be64(&src[ndigits - 1 - i]);
}

/**
--
2.30.2