Accesses to hci_dev->remote_oob_data are protected by the hdev lock,
except for the access in build_pairing_cmd via hci_find_remote_oob_data.
Adding the lock around the access in build_pairing_cmd would cause a
lock ordering problem: the l2cap_chan_lock is taken in the caller
smp_conn_security, while the hdev lock should be taken before the chan
lock.
The solution is to add the hdev lock to the callsites of
build_pairing_cmd.
Fixes: 02b05bd8b0a6 ("Bluetooth: Set SMP OOB flag if OOB data is available")
Signed-off-by: Niels Dossche <dossche.niels@xxxxxxxxx>
---
Note:
I am currently working on a static analyser to detect missing locks
using type-based static analysis, which reported the missing lock on
v6.0-rc5. I manually verified the report by looking at the code,
so that I do not send wrong information or patches.
After concluding that this seems to be a true positive, I created
this patch. I have only managed to compile-test this patch on x86_64.
After applying the patch, my analyser no longer reports the potential
bug.
net/bluetooth/smp.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/net/bluetooth/smp.c b/net/bluetooth/smp.c
index 11f853d0500f..3efa99fa5062 100644
--- a/net/bluetooth/smp.c
+++ b/net/bluetooth/smp.c
@@ -1803,7 +1803,9 @@ static u8 smp_cmd_pairing_req(struct l2cap_conn *conn, struct sk_buff *skb)
return 0;
}
+ hci_dev_lock(dev);
build_pairing_cmd(conn, req, &rsp, auth);
+ hci_dev_unlock(hdev);
if (rsp.auth_req & SMP_AUTH_SC) {
set_bit(SMP_FLAG_SC, &smp->flags);
@@ -2335,7 +2337,9 @@ static u8 smp_cmd_security_req(struct l2cap_conn *conn, struct sk_buff *skb)
skb_pull(skb, sizeof(*rp));
memset(&cp, 0, sizeof(cp));
+ hci_dev_lock(hdev);
build_pairing_cmd(conn, &cp, NULL, auth);
+ hci_dev_unlock(hdev);
smp->preq[0] = SMP_CMD_PAIRING_REQ;
memcpy(&smp->preq[1], &cp, sizeof(cp));
@@ -2380,6 +2384,7 @@ int smp_conn_security(struct hci_conn *hcon, __u8 sec_level)
return 1;
}
+ hci_dev_lock(hcon->hdev);
l2cap_chan_lock(chan);
/* If SMP is already in progress ignore this request */
@@ -2435,6 +2440,7 @@ int smp_conn_security(struct hci_conn *hcon, __u8 sec_level)
unlock:
l2cap_chan_unlock(chan);
+ hci_dev_unlock(hcon->hdev);
return ret;
}
--
2.37.3
