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-rw-r--r--main/hostapd/0002-OpenSSL-Use-constant-time-selection-for-crypto_bignu.patch60
1 files changed, 60 insertions, 0 deletions
diff --git a/main/hostapd/0002-OpenSSL-Use-constant-time-selection-for-crypto_bignu.patch b/main/hostapd/0002-OpenSSL-Use-constant-time-selection-for-crypto_bignu.patch
new file mode 100644
index 0000000000..8e635c1371
--- /dev/null
+++ b/main/hostapd/0002-OpenSSL-Use-constant-time-selection-for-crypto_bignu.patch
@@ -0,0 +1,60 @@
+From c93461c1d98f52681717a088776ab32fd97872b0 Mon Sep 17 00:00:00 2001
+From: Jouni Malinen <jouni@codeaurora.org>
+Date: Fri, 8 Mar 2019 00:24:12 +0200
+Subject: [PATCH] OpenSSL: Use constant time selection for
+ crypto_bignum_legendre()
+
+Get rid of the branches that depend on the result of the Legendre
+operation. This is needed to avoid leaking information about different
+temporary results in blinding mechanisms.
+
+This is related to CVE-2019-9494 and CVE-2019-9495.
+
+Signed-off-by: Jouni Malinen <jouni@codeaurora.org>
+---
+ src/crypto/crypto_openssl.c | 15 +++++++++------
+ 1 file changed, 9 insertions(+), 6 deletions(-)
+
+diff --git a/src/crypto/crypto_openssl.c b/src/crypto/crypto_openssl.c
+index ac53cc81a..0f52101ea 100644
+--- a/src/crypto/crypto_openssl.c
++++ b/src/crypto/crypto_openssl.c
+@@ -24,6 +24,7 @@
+ #endif /* CONFIG_ECC */
+
+ #include "common.h"
++#include "utils/const_time.h"
+ #include "wpabuf.h"
+ #include "dh_group5.h"
+ #include "sha1.h"
+@@ -1500,6 +1501,7 @@ int crypto_bignum_legendre(const struct crypto_bignum *a,
+ BN_CTX *bnctx;
+ BIGNUM *exp = NULL, *tmp = NULL;
+ int res = -2;
++ unsigned int mask;
+
+ if (TEST_FAIL())
+ return -2;
+@@ -1518,12 +1520,13 @@ int crypto_bignum_legendre(const struct crypto_bignum *a,
+ (const BIGNUM *) p, bnctx, NULL))
+ goto fail;
+
+- if (BN_is_word(tmp, 1))
+- res = 1;
+- else if (BN_is_zero(tmp))
+- res = 0;
+- else
+- res = -1;
++ /* Return 1 if tmp == 1, 0 if tmp == 0, or -1 otherwise. Need to use
++ * constant time selection to avoid branches here. */
++ res = -1;
++ mask = const_time_eq(BN_is_word(tmp, 1), 1);
++ res = const_time_select_int(mask, 1, res);
++ mask = const_time_eq(BN_is_zero(tmp), 1);
++ res = const_time_select_int(mask, 0, res);
+
+ fail:
+ BN_clear_free(tmp);
+--
+2.21.0
+