crypto: nx - fix nx_crypto_ctx_exit argument

commit 4e67f50 upstream.

nx_crypto_ctx_shash_exit calls nx_crypto_ctx_exit with crypto_shash_ctx(...)
but crypto_shash_ctx gives a nx_crypto_ctx *, not a crypto_tfm *.

Fix the type in nx_crypto_ctx_exit and drop the bogus crypto_tfm_ctx
call.

This fixes the following oops:

  BUG: Unable to handle kernel data access at 0xc0403effffffffc8
  Faulting instruction address: 0xc000000000396cb4
  Oops: Kernel access of bad area, sig: 11 [#15]
  Call Trace:
   nx_crypto_ctx_shash_exit+0x24/0x60
   crypto_shash_exit_tfm+0x28/0x40
   crypto_destroy_tfm+0x98/0x140
   crypto_exit_ahash_using_shash+0x20/0x40
   crypto_destroy_tfm+0x98/0x140
   hash_release+0x1c/0x30
   alg_sock_destruct+0x38/0x60
   __sk_destruct+0x48/0x2b0
   af_alg_release+0x58/0xb0
   __sock_release+0x68/0x150
   sock_close+0x20/0x40
   __fput+0x110/0x3a0
   sys_close+0x48/0xa0
   system_call_exception+0x140/0x2d0
   system_call_common+0xf4/0x258

.. which came from hardlink(1) opportunistically using AF_ALG.

The same problem exists with nx_crypto_ctx_skcipher_exit getting a context
it wasn't expecting, but apparently nobody hit that for years.

Cc: Eric Biggers <ebiggers@kernel.org>
Cc: stable@vger.kernel.org
Fixes: bfd9efd ("crypto: nx - convert AES-ECB to skcipher API")
Fixes: 9420e62 ("crypto: nx - Use API partial block handling")
Acked-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Eric Biggers <ebiggers@kernel.org>
Reported-by: Calvin Buckley <calvin@cmpct.info>
Tested-by: Calvin Buckley <calvin@cmpct.info>
Suggested-by: Brad Spengler <brad.spengler@opensrcsec.com>
Signed-off-by: Sam James <sam@gentoo.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: thesamesam

drivers/crypto/nx/nx.c

@@ -714,15 +714,13 @@ int nx_crypto_ctx_aes_xcbc_init(struct crypto_shash *tfm)
 /**
  * nx_crypto_ctx_exit - destroy a crypto api context
  *
- * @tfm: the crypto transform pointer for the context
+ * @nx_ctx: the crypto api context
  *
  * As crypto API contexts are destroyed, this exit hook is called to free the
  * memory associated with it.
  */
-void nx_crypto_ctx_exit(struct crypto_tfm *tfm)
+void nx_crypto_ctx_exit(struct nx_crypto_ctx *nx_ctx)
 {
-	struct nx_crypto_ctx *nx_ctx = crypto_tfm_ctx(tfm);
-
 	kfree_sensitive(nx_ctx->kmem);
 	nx_ctx->csbcpb = NULL;
 	nx_ctx->csbcpb_aead = NULL;

drivers/crypto/nx/nx.h

@@ -153,7 +153,7 @@ int nx_crypto_ctx_aes_ctr_init(struct crypto_skcipher *tfm);
 int nx_crypto_ctx_aes_cbc_init(struct crypto_skcipher *tfm);
 int nx_crypto_ctx_aes_ecb_init(struct crypto_skcipher *tfm);
 int nx_crypto_ctx_sha_init(struct crypto_shash *tfm);
-void nx_crypto_ctx_exit(struct crypto_tfm *tfm);
+void nx_crypto_ctx_exit(struct nx_crypto_ctx *nx_ctx);
 void nx_crypto_ctx_skcipher_exit(struct crypto_skcipher *tfm);
 void nx_crypto_ctx_aead_exit(struct crypto_aead *tfm);
 void nx_crypto_ctx_shash_exit(struct crypto_shash *tfm);