linux-kernel - [PATCH] crypto: lib/mpi - Fix unexpected pointer access

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Date:   Thu, 14 Dec 2023 11:08:34 +0800
From:   Tianjia Zhang <tianjia.zhang@...ux.alibaba.com>
To:     Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>,
        Mimi Zohar <zohar@...ux.ibm.com>, linux-crypto@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     Tianjia Zhang <tianjia.zhang@...ux.alibaba.com>
Subject: [PATCH] crypto: lib/mpi - Fix unexpected pointer access

When the mpi_ec_ctx structure is initialized, some fields are not
cleared, causing a crash when referencing the field when the
structure was released. Initially, this issue was ignored because
memory for mpi_ec_ctx is allocated with the __GFP_ZERO flag.
For example, this error will be triggered when calculating the
Za value for SM2 separately.

Fixes: d58bb7e55a8a ("lib/mpi: Introduce ec implementation to MPI library")
Cc: stable@...r.kernel.org # v6.5
Signed-off-by: Tianjia Zhang <tianjia.zhang@...ux.alibaba.com>
---
 lib/crypto/mpi/ec.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/lib/crypto/mpi/ec.c b/lib/crypto/mpi/ec.c
index 40f5908e57a4..e16dca1e23d5 100644
--- a/lib/crypto/mpi/ec.c
+++ b/lib/crypto/mpi/ec.c
@@ -584,6 +584,9 @@ void mpi_ec_init(struct mpi_ec_ctx *ctx, enum gcry_mpi_ec_models model,
 	ctx->a = mpi_copy(a);
 	ctx->b = mpi_copy(b);
 
+	ctx->d = NULL;
+	ctx->t.two_inv_p = NULL;
+
 	ctx->t.p_barrett = use_barrett > 0 ? mpi_barrett_init(ctx->p, 0) : NULL;
 
 	mpi_ec_get_reset(ctx);
-- 
2.24.3 (Apple Git-128)