[PATCH v2] Bluetooth: hci_sync: fix refcounting in le_read_features_complete

[PATCH v2] Bluetooth: hci_sync: fix refcounting in le_read_features_complete

[Pauli Virtanen]

hci_conn_get() refcount acquired in hci_le_read_remote_features() must
be unconditionally released in the destructor, or it leaks.  The
destructor is always called if hci_cmd_sync_queue_once() returned with
success.

It also looks like removing the hold/drop logical refcounting here by
commit 60562bebb651 ("Bluetooth: hci_sync: Fix UAF in le_read_features_complete")
caused a behavior change (mgmt-tester Adv. / Ext. Adv. test failures).

Fix the destructor le_read_features_complete() to always release the
refcount.

Also restore the logical hold/drop refcount, preventing the hci_conn
from timing out during this command.

Fixes: 60562bebb651 ("Bluetooth: hci_sync: Fix UAF in le_read_features_complete")
Signed-off-by: Pauli Virtanen <pav@iki.fi>
---

Notes:
    v2:
    - restore also the hold/drop refcounting
    
    This probably should be fixup in bluetooth-next/master if it wasn't
    pulled yet.
    
    Restoring the hold/drop makes the following mgmt-tester tests pass
    again:
    
    Adv. connectable & connected (central) - Success
    Adv. non-connectable & connected (central) - Success
    Ext Adv. connectable & connected (central)
    Ext Adv. non-connectable & connected (central)
    
    It's not clear to me whether there is something wrong with these tests,
    but probably the behavior change was unintended so it's better to
    restore it.

 net/bluetooth/hci_sync.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c
index 91d0252ae661..0c6baba4e69c 100644
--- a/net/bluetooth/hci_sync.c
+++ b/net/bluetooth/hci_sync.c
@@ -7390,9 +7390,7 @@ static void le_read_features_complete(struct hci_dev *hdev, void *data, int err)
 
 	bt_dev_dbg(hdev, "err %d", err);
 
-	if (err == -ECANCELED)
-		return;
-
+	hci_conn_drop(conn);
 	hci_conn_put(conn);
 }
 
@@ -7463,10 +7461,12 @@ int hci_le_read_remote_features(struct hci_conn *conn)
 	if (conn->out || (hdev->le_features[0] & HCI_LE_PERIPHERAL_FEATURES)) {
 		err = hci_cmd_sync_queue_once(hdev,
 					      hci_le_read_remote_features_sync,
-					      hci_conn_get(conn),
+					      hci_conn_hold(hci_conn_get(conn)),
 					      le_read_features_complete);
-		if (err)
+		if (err) {
+			hci_conn_drop(conn);
 			hci_conn_put(conn);
+		}
 	} else {
 		err = -EOPNOTSUPP;
 	}
-- 
2.53.0

RE: [v2] Bluetooth: hci_sync: fix refcounting in le_read_features_complete

[bluez.test.bot]

[-- Attachment #1: Type: text/plain, Size: 2593 bytes --]

This is automated email and please do not reply to this email!

Dear submitter,

Thank you for submitting the patches to the linux bluetooth mailing list.
This is a CI test results with your patch series:
PW Link:https://patchwork.kernel.org/project/bluetooth/list/?series=1074221

---Test result---

Test Summary:
CheckPatch                    PENDING   0.30 seconds
GitLint                       PENDING   0.25 seconds
SubjectPrefix                 PASS      0.10 seconds
BuildKernel                   PASS      25.91 seconds
CheckAllWarning               PASS      28.29 seconds
CheckSparse                   PASS      27.22 seconds
BuildKernel32                 PASS      25.10 seconds
TestRunnerSetup               PASS      560.73 seconds
TestRunner_l2cap-tester       PASS      27.63 seconds
TestRunner_iso-tester         PASS      39.73 seconds
TestRunner_bnep-tester        PASS      6.25 seconds
TestRunner_mgmt-tester        FAIL      115.26 seconds
TestRunner_rfcomm-tester      PASS      9.94 seconds
TestRunner_sco-tester         FAIL      14.84 seconds
TestRunner_ioctl-tester       PASS      10.58 seconds
TestRunner_mesh-tester        FAIL      12.46 seconds
TestRunner_smp-tester         PASS      8.78 seconds
TestRunner_userchan-tester    PASS      7.00 seconds
IncrementalBuild              PENDING   1.00 seconds

Details
##############################
Test: CheckPatch - PENDING
Desc: Run checkpatch.pl script
Output:

##############################
Test: GitLint - PENDING
Desc: Run gitlint
Output:

##############################
Test: TestRunner_mgmt-tester - FAIL
Desc: Run mgmt-tester with test-runner
Output:
Total: 494, Passed: 489 (99.0%), Failed: 1, Not Run: 4

Failed Test Cases
Read Exp Feature - Success                           Failed       0.115 seconds
##############################
Test: TestRunner_sco-tester - FAIL
Desc: Run sco-tester with test-runner
Output:
WARNING: possible circular locking dependency detected
BUG: sleeping function called from invalid context at net/core/sock.c:3782
Total: 30, Passed: 30 (100.0%), Failed: 0, Not Run: 0
##############################
Test: TestRunner_mesh-tester - FAIL
Desc: Run mesh-tester with test-runner
Output:
Total: 10, Passed: 8 (80.0%), Failed: 2, Not Run: 0

Failed Test Cases
Mesh - Send cancel - 1                               Timed out    2.512 seconds
Mesh - Send cancel - 2                               Timed out    1.996 seconds
##############################
Test: IncrementalBuild - PENDING
Desc: Incremental build with the patches in the series
Output:



---
Regards,
Linux Bluetooth