From 8a984fc1dd91da2100ea93e3b44775c3606ee364 Mon Sep 17 00:00:00 2001 From: tabudz <64760144+tabudz@users.noreply.github.com> Date: Wed, 26 Feb 2025 16:44:12 +0800 Subject: [PATCH] mt7603e: fix possible infinite loop in BN_mod_sqrt() (#13368) The calculation in some cases does not finish for non-prime p. This fixes CVE-2022-0778. Based on patch by David Benjamin . Reviewed-by: Paul Dale Reviewed-by: Matt Caswell --- .../mt7603e/src/mt7603_wifi/common/bn_lib.c | 32 ++++++++++--------- 1 file changed, 17 insertions(+), 15 deletions(-) diff --git a/package/lean/mt/drivers/mt7603e/src/mt7603_wifi/common/bn_lib.c b/package/lean/mt/drivers/mt7603e/src/mt7603_wifi/common/bn_lib.c index 1cabc7f97..ec46196ba 100644 --- a/package/lean/mt/drivers/mt7603e/src/mt7603_wifi/common/bn_lib.c +++ b/package/lean/mt/drivers/mt7603e/src/mt7603_wifi/common/bn_lib.c @@ -6555,7 +6555,8 @@ BIGNUM *BN_mod_sqrt(BIGNUM *in, const BIGNUM *a, const BIGNUM *p, BN_CTX *ctx) /* * Returns 'ret' such that ret^2 == a (mod p), using the Tonelli/Shanks * algorithm (cf. Henri Cohen, "A Course in Algebraic Computational Number - * Theory", algorithm 1.5.1). 'p' must be prime! + * Theory", algorithm 1.5.1). 'p' must be prime, otherwise an error or + * an incorrect "result" will be returned. */ { BIGNUM *ret = in; @@ -6871,22 +6872,23 @@ BIGNUM *BN_mod_sqrt(BIGNUM *in, const BIGNUM *a, const BIGNUM *p, BN_CTX *ctx) goto vrfy; } - /* find smallest i such that b^(2^i) = 1 */ - i = 1; - - if (!BN_mod_sqr(t, b, p, ctx)) - goto end; - - while (!BN_is_one(t)) { - i++; - - if (i == e) { - BNerr(BN_F_BN_MOD_SQRT, BN_R_NOT_A_SQUARE); - goto end; + /* Find the smallest i, 0 < i < e, such that b^(2^i) = 1. */ + for (i = 1; i < e; i++) { + if (i == 1) { + if (!BN_mod_sqr(t, b, p, ctx)) + goto end; + } else { + if (!BN_mod_mul(t, t, t, p, ctx)) + goto end; } - if (!BN_mod_mul(t, t, t, p, ctx)) - goto end; + if (BN_is_one(t)) + break; + } + /* If not found, a is not a square or p is not prime. */ + if (i >= e) { + BNerr(BN_F_BN_MOD_SQRT, BN_R_NOT_A_SQUARE); + goto end; } /* t := y^2^(e - i - 1) */