[5.3,090/105] crypto: ecdh - fix big endian bug in ECC library

Message ID 20191211150300.743726216@linuxfoundation.org
State Superseded
Headers show
  • Untitled series #25614
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Commit Message

Greg Kroah-Hartman Dec. 11, 2019, 3:06 p.m.
From: Ard Biesheuvel <ard.biesheuvel@linaro.org>

commit f398243e9fd6a3a059c1ea7b380c40628dbf0c61 upstream.

The elliptic curve arithmetic library used by the EC-DH KPP implementation
assumes big endian byte order, and unconditionally reverses the byte
and word order of multi-limb quantities. On big endian systems, the byte
reordering is not necessary, while the word ordering needs to be retained.

So replace the __swab64() invocation with a call to be64_to_cpu() which
should do the right thing for both little and big endian builds.

Fixes: 3c4b23901a0c ("crypto: ecdh - Add ECDH software support")
Cc: <stable@vger.kernel.org> # v4.9+
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

 crypto/ecc.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)


--- a/crypto/ecc.c
+++ b/crypto/ecc.c
@@ -1284,10 +1284,11 @@  EXPORT_SYMBOL(ecc_point_mult_shamir);
 static inline void ecc_swap_digits(const u64 *in, u64 *out,
 				   unsigned int ndigits)
+	const __be64 *src = (__force __be64 *)in;
 	int i;
 	for (i = 0; i < ndigits; i++)
-		out[i] = __swab64(in[ndigits - 1 - i]);
+		out[i] = be64_to_cpu(src[ndigits - 1 - i]);
 static int __ecc_is_key_valid(const struct ecc_curve *curve,