[PATCH] crypto: ecc: handle unaligned input buffer in ecc_swap_digits

[PATCH] crypto: ecc: handle unaligned input buffer in ecc_swap_digits

[Mian Yousaf Kaukab]

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>
---
 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]);
 }
 
 /**
-- 
2.26.2

Re: [PATCH] crypto: ecc: handle unaligned input buffer in ecc_swap_digits

[Stefan Berger]

On 7/21/21 4:39 AM, Mian Yousaf Kaukab wrote:
> 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>


> ---
>   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]);
>   }
>   
>   /**

Re: [PATCH] crypto: ecc: handle unaligned input buffer in ecc_swap_digits

[Herbert Xu]

On Wed, Jul 21, 2021 at 10:39:05AM +0200, Mian Yousaf Kaukab wrote:
> 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>
> ---
>  crypto/ecc.h | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)

Patch applied.  Thanks.
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt