crypto: drbg - Only fail when jent is unavailable in FIPS mode

stable inclusion
from stable-v4.19.283
commit 1fd247c1ded58f9bc1130fe4b26fb187fa1af55d
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I7BZ5U
CVE: NA

--------------------------------

[ Upstream commit 686cd976 ]

When jent initialisation fails for any reason other than ENOENT,
the entire drbg fails to initialise, even when we're not in FIPS
mode.  This is wrong because we can still use the kernel RNG when
we're not in FIPS mode.

Change it so that it only fails when we are in FIPS mode.

Fixes: 57225e67 ("crypto: drbg - Use callback API for random readiness")
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>
Reviewed-by: NStephan Mueller <smueller@chronox.de>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NYongqiang Liu <liuyongqiang13@huawei.com>

crypto/drbg.c

@@ -1429,7 +1429,7 @@ static int drbg_prepare_hrng(struct drbg_state *drbg)
 		const int err = PTR_ERR(drbg->jent);
 
 		drbg->jent = NULL;
-		if (fips_enabled || err != -ENOENT)
+		if (fips_enabled)
 			return err;
 		pr_info("DRBG: Continuing without Jitter RNG\n");
 	}