crypto: caam - fix signals handling

Driver does not properly handle the case when signals interrupt
wait_for_completion_interruptible():
-it does not check for return value
-completion structure is allocated on stack; in case a signal interrupts
the sleep, it will go out of scope, causing the worker thread
(caam_jr_dequeue) to fail when it accesses it

wait_for_completion_interruptible() is replaced with uninterruptable
wait_for_completion().
We choose to block all signals while waiting for I/O (device executing
the split key generation job descriptor) since the alternative - in
order to have a deterministic device state - would be to flush the job
ring (aborting *all* in-progress jobs).

Cc: <stable@vger.kernel.org>
Fixes: 045e3678 ("crypto: caam - ahash hmac support")
Fixes: 4c1ec1f9 ("crypto: caam - refactor key_gen, sg")
Signed-off-by: Horia Geantă <horia.geanta@nxp.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/caam/caamhash.c

@@ -396,7 +396,7 @@ static int hash_digest_key(struct caam_hash_ctx *ctx, const u8 *key_in,
 	ret = caam_jr_enqueue(jrdev, desc, split_key_done, &result);
 	if (!ret) {
 		/* in progress */
-		wait_for_completion_interruptible(&result.completion);
+		wait_for_completion(&result.completion);
 		ret = result.err;
 #ifdef DEBUG
 		print_hex_dump(KERN_ERR,

drivers/crypto/caam/key_gen.c

@@ -149,7 +149,7 @@ int gen_split_key(struct device *jrdev, u8 *key_out,
 	ret = caam_jr_enqueue(jrdev, desc, split_key_done, &result);
 	if (!ret) {
 		/* in progress */
-		wait_for_completion_interruptible(&result.completion);
+		wait_for_completion(&result.completion);
 		ret = result.err;
 #ifdef DEBUG
 		print_hex_dump(KERN_ERR, "ctx.key@"__stringify(__LINE__)": ",