[PATCH v4 04/10] crypto: padlock-aes - clear the crypto_aes_ctx when done

[Thomas Huth]

From: Thomas Huth <thuth@xxxxxxxxxx>

Clear the crypto_aes_ctx structure via __cleanup(aes_zeroize_ctx)
when we're done with it to avoid that key data could leak on the
stack.

And since __cleanup() (and __free()) should not be mixed with
"gotos" in the same function, turn the goto statement here
into a proper block of the related if-statement.

Signed-off-by: Thomas Huth <thuth@xxxxxxxxxx>
---
 drivers/crypto/padlock-aes.c | 22 ++++++++++------------
 1 file changed, 10 insertions(+), 12 deletions(-)

diff --git a/drivers/crypto/padlock-aes.c b/drivers/crypto/padlock-aes.c
index 1be549a07a219..400a889e924d7 100644
--- a/drivers/crypto/padlock-aes.c
+++ b/drivers/crypto/padlock-aes.c
@@ -109,7 +109,7 @@ static int aes_set_key(struct crypto_tfm *tfm, const u8 *in_key,
 {
 	struct aes_ctx *ctx = aes_ctx(tfm);
 	const __le32 *key = (const __le32 *)in_key;
-	struct crypto_aes_ctx gen_aes;
+	struct crypto_aes_ctx gen_aes __cleanup(aes_zeroize_ctx);
 	int cpu;
 
 	if (key_len % 8)
@@ -137,20 +137,18 @@ static int aes_set_key(struct crypto_tfm *tfm, const u8 *in_key,
 	ctx->cword.decrypt.ksize = ctx->cword.encrypt.ksize;
 
 	/* Don't generate extended keys if the hardware can do it. */
-	if (aes_hw_extkey_available(key_len))
-		goto ok;
+	if (!aes_hw_extkey_available(key_len)) {
+		ctx->D = ctx->d_data;
+		ctx->cword.encrypt.keygen = 1;
+		ctx->cword.decrypt.keygen = 1;
 
-	ctx->D = ctx->d_data;
-	ctx->cword.encrypt.keygen = 1;
-	ctx->cword.decrypt.keygen = 1;
+		if (aes_expandkey(&gen_aes, in_key, key_len))
+			return -EINVAL;
 
-	if (aes_expandkey(&gen_aes, in_key, key_len))
-		return -EINVAL;
-
-	memcpy(ctx->E, gen_aes.key_enc, AES_MAX_KEYLENGTH);
-	memcpy(ctx->D, gen_aes.key_dec, AES_MAX_KEYLENGTH);
+		memcpy(ctx->E, gen_aes.key_enc, AES_MAX_KEYLENGTH);
+		memcpy(ctx->D, gen_aes.key_dec, AES_MAX_KEYLENGTH);
+	}
 
-ok:
 	for_each_online_cpu(cpu)
 		if (&ctx->cword.encrypt == per_cpu(paes_last_cword, cpu) ||
 		    &ctx->cword.decrypt == per_cpu(paes_last_cword, cpu))
-- 
2.55.0