| Message ID | 20220913152016.38691-1-dossche.niels@gmail.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | Bluetooth: protect remote oob data in build_pairing_cmd's callsites | expand |
On 9/13/22 17:20, Niels Dossche wrote: > 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@gmail.com> > --- > > 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; > } > I'm sorry. The build failure is because I forgot to amend my commit locally. I've sent a v2 with all the changes.
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; }
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@gmail.com> --- 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(+)