From: Mincheol Son <encrypted.def@gmail.com>
To: marcel@holtmann.org
Cc: johan.hedberg@gmail.com, davem@davemloft.net, kuba@kernel.org,
linux-bluetooth@vger.kernel.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org,
Mincheol Son <encrypted.def@gmail.com>
Subject: [PATCH] Bluetooth: smp: Fix biased random passkey generation
Date: Tue, 8 Dec 2020 02:49:57 +0900 [thread overview]
Message-ID: <20201207174957.408-1-encrypted.def@gmail.com> (raw)
Since u32 range size is not a multiple of 1,000,000, current passkey generation logic is biased.
Fixed this by adding a routine that selects passkey again if passkey is 4,200,000,000 or more.
Signed-off-by: Mincheol Son <encrypted.def@gmail.com>
---
net/bluetooth/smp.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/net/bluetooth/smp.c b/net/bluetooth/smp.c
index c659c464f7ca..26ed83e0db34 100644
--- a/net/bluetooth/smp.c
+++ b/net/bluetooth/smp.c
@@ -922,7 +922,9 @@ static int tk_request(struct l2cap_conn *conn, u8 remote_oob, u8 auth,
/* Generate random passkey. */
if (smp->method == CFM_PASSKEY) {
memset(smp->tk, 0, sizeof(smp->tk));
- get_random_bytes(&passkey, sizeof(passkey));
+ do {
+ get_random_bytes(&passkey, sizeof(passkey));
+ } while (passkey >= (u32)4200000000);
passkey %= 1000000;
put_unaligned_le32(passkey, smp->tk);
BT_DBG("PassKey: %d", passkey);
--
2.25.1
next reply other threads:[~2020-12-07 17:51 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-07 17:49 Mincheol Son [this message]
2020-12-07 21:27 ` [PATCH] Bluetooth: smp: Fix biased random passkey generation kernel test robot
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