linux-kernel - [PATCH] crypto: arm/aes-neonbs - fix usage of cbc(aes) fallback

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Message-Id: <20201028090320.4222-1-horia.geanta@nxp.com>
Date:   Wed, 28 Oct 2020 11:03:20 +0200
From:   Horia Geantă <horia.geanta@....com>
To:     Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>
Cc:     Russell King <linux@...linux.org.uk>,
        Ard Biesheuvel <ardb@...nel.org>, linux-crypto@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        NXP Linux Team <linux-imx@....com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH] crypto: arm/aes-neonbs - fix usage of cbc(aes) fallback

Loading the module deadlocks since:
-local cbc(aes) implementation needs a fallback and
-crypto API tries to find one but the request_module() resolves back to
the same module

Fix this by changing the module alias for cbc(aes) and
using the NEED_FALLBACK flag when requesting for a fallback algorithm.

Fixes: 00b99ad2bac2 ("crypto: arm/aes-neonbs - Use generic cbc encryption path")
Signed-off-by: Horia Geantă <horia.geanta@....com>
---
 arch/arm/crypto/aes-neonbs-glue.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/arch/arm/crypto/aes-neonbs-glue.c b/arch/arm/crypto/aes-neonbs-glue.c
index bda8bf17631e..f70af1d0514b 100644
--- a/arch/arm/crypto/aes-neonbs-glue.c
+++ b/arch/arm/crypto/aes-neonbs-glue.c
@@ -19,7 +19,7 @@ MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@...aro.org>");
 MODULE_LICENSE("GPL v2");
 
 MODULE_ALIAS_CRYPTO("ecb(aes)");
-MODULE_ALIAS_CRYPTO("cbc(aes)");
+MODULE_ALIAS_CRYPTO("cbc(aes)-all");
 MODULE_ALIAS_CRYPTO("ctr(aes)");
 MODULE_ALIAS_CRYPTO("xts(aes)");
 
@@ -191,7 +191,8 @@ static int cbc_init(struct crypto_skcipher *tfm)
 	struct aesbs_cbc_ctx *ctx = crypto_skcipher_ctx(tfm);
 	unsigned int reqsize;
 
-	ctx->enc_tfm = crypto_alloc_skcipher("cbc(aes)", 0, CRYPTO_ALG_ASYNC);
+	ctx->enc_tfm = crypto_alloc_skcipher("cbc(aes)", 0, CRYPTO_ALG_ASYNC |
+					     CRYPTO_ALG_NEED_FALLBACK);
 	if (IS_ERR(ctx->enc_tfm))
 		return PTR_ERR(ctx->enc_tfm);
 
@@ -441,7 +442,8 @@ static struct skcipher_alg aes_algs[] = { {
 	.base.cra_blocksize	= AES_BLOCK_SIZE,
 	.base.cra_ctxsize	= sizeof(struct aesbs_cbc_ctx),
 	.base.cra_module	= THIS_MODULE,
-	.base.cra_flags		= CRYPTO_ALG_INTERNAL,
+	.base.cra_flags		= CRYPTO_ALG_INTERNAL |
+				  CRYPTO_ALG_NEED_FALLBACK,
 
 	.min_keysize		= AES_MIN_KEY_SIZE,
 	.max_keysize		= AES_MAX_KEY_SIZE,
-- 
2.17.1