[PATCH] libceph: don't WARN() if user tries to add invalid key

[Eric Biggers <ebiggers3@gmail.com>]

From: Eric Biggers <ebiggers@google.com>

The WARN_ON(!key->len) in set_secret() in net/ceph/crypto.c is hit if a
user tries to add a key of type "ceph" with an invalid payload as
follows (assuming CONFIG_CEPH_LIB=y):

    echo -e -n '\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00' \
	| keyctl padd ceph desc @s

This can be hit by fuzzers.  As this is merely bad input and not a
kernel bug, replace the WARN_ON() with return -EINVAL.

Fixes: 7af3ea189a9a ("libceph: stop allocating a new cipher on every crypto request")
Cc: <stable@vger.kernel.org> # v4.10+
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 net/ceph/crypto.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/ceph/crypto.c b/net/ceph/crypto.c
index 489610ac1cdd..bf9d079cbafd 100644
--- a/net/ceph/crypto.c
+++ b/net/ceph/crypto.c
@@ -37,7 +37,9 @@ static int set_secret(struct ceph_crypto_key *key, void *buf)
 		return -ENOTSUPP;
 	}
 
-	WARN_ON(!key->len);
+	if (!key->len)
+		return -EINVAL;
+
 	key->key = kmemdup(buf, key->len, GFP_NOIO);
 	if (!key->key) {
 		ret = -ENOMEM;
-- 
2.15.0