From patchwork Sun May 3 11:26:34 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Heiko Stuebner X-Patchwork-Id: 244883 List-Id: U-Boot discussion From: heiko at sntech.de (Heiko Stuebner) Date: Sun, 3 May 2020 13:26:34 +0200 Subject: [PATCH] rsa: fix alignment issue when getting public exponent Message-ID: <20200503112634.590399-1-heiko@sntech.de> From: Heiko Stuebner To fill the exponent field of the rsa_public_key struct, rsa_mod_exp_sw did a cast to uint64_t of the key_prop->public_exponent field. But that alignment is not guaranteed in all cases. This came to light when in my spl-fit-signature the key-name exceeded a certain length and with it the verification then started failing. (naming it "integrity" worked fine, "integrity-uboot" failed) key_prop.public_exponent itself is actually a void-pointer, fdt_getprop() also just returns such a void-pointer and inside the devicetree the 64bit exponent is represented as 2 32bit numbers, so assuming a 64bit alignment can lead to false reads. So just use the already existing rsa_convert_big_endian() to do the actual conversion from the dt's big-endian to the needed uint64 value. Fixes: fc2f4246b4b3 ("rsa: Split the rsa-verify to separate the modular exponentiation") Signed-off-by: Heiko Stuebner Reviewed-by: Philipp Tomsich Reviewed-by: Simon Glass Tested-by: Jan Kiszka --- lib/rsa/rsa-mod-exp.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/lib/rsa/rsa-mod-exp.c b/lib/rsa/rsa-mod-exp.c index 420ab2eba0..62b2557cc2 100644 --- a/lib/rsa/rsa-mod-exp.c +++ b/lib/rsa/rsa-mod-exp.c @@ -262,8 +262,8 @@ int rsa_mod_exp_sw(const uint8_t *sig, uint32_t sig_len, if (!prop->public_exponent) key.exponent = RSA_DEFAULT_PUBEXP; else - key.exponent = - fdt64_to_cpu(*((uint64_t *)(prop->public_exponent))); + rsa_convert_big_endian((uint32_t *)&key.exponent, + prop->public_exponent, 2); if (!key.len || !prop->modulus || !prop->rr) { debug("%s: Missing RSA key info", __func__);