2023-04-03 21:34:58

by Luiz Augusto von Dentz

[permalink] [raw]
Subject: [PATCH] Bluetooth: hci_conn: Fix possible UAF

From: Luiz Augusto von Dentz <[email protected]>

This fixes the following trace:

==================================================================
BUG: KASAN: slab-use-after-free in hci_conn_del+0xba/0x3a0
Write of size 8 at addr ffff88800208e9c8 by task iso-tester/31

CPU: 0 PID: 31 Comm: iso-tester Not tainted 6.3.0-rc2-g991aa4a69a47
#4716
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.1-2.fc36
04/01/2014
Call Trace:
<TASK>
dump_stack_lvl+0x1d/0x70
print_report+0xce/0x610
? __virt_addr_valid+0xd4/0x150
? hci_conn_del+0xba/0x3a0
kasan_report+0xdd/0x110
? hci_conn_del+0xba/0x3a0
hci_conn_del+0xba/0x3a0
hci_conn_hash_flush+0xf2/0x120
hci_dev_close_sync+0x388/0x920
hci_unregister_dev+0x122/0x260
vhci_release+0x4f/0x90
__fput+0x102/0x430
task_work_run+0xf1/0x160
? __pfx_task_work_run+0x10/0x10
? mark_held_locks+0x24/0x90
exit_to_user_mode_prepare+0x170/0x180
syscall_exit_to_user_mode+0x19/0x50
do_syscall_64+0x4e/0x90
entry_SYSCALL_64_after_hwframe+0x70/0xda

Fixes: 0f00cd322d22 ("Bluetooth: Free potentially unfreed SCO connection")
Signed-off-by: Luiz Augusto von Dentz <[email protected]>
---
net/bluetooth/hci_conn.c | 30 ++++++++++++++++++++++++------
1 file changed, 24 insertions(+), 6 deletions(-)

diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
index fe8d54f8f04f..5672b4924572 100644
--- a/net/bluetooth/hci_conn.c
+++ b/net/bluetooth/hci_conn.c
@@ -1069,6 +1069,17 @@ struct hci_conn *hci_conn_add(struct hci_dev *hdev, int type, bdaddr_t *dst,
return conn;
}

+static bool hci_conn_unlink(struct hci_conn *conn)
+{
+ if (!conn->link)
+ return false;
+
+ conn->link->link = NULL;
+ conn->link = NULL;
+
+ return true;
+}
+
int hci_conn_del(struct hci_conn *conn)
{
struct hci_dev *hdev = conn->hdev;
@@ -1080,15 +1091,16 @@ int hci_conn_del(struct hci_conn *conn)
cancel_delayed_work_sync(&conn->idle_work);

if (conn->type == ACL_LINK) {
- struct hci_conn *sco = conn->link;
- if (sco) {
- sco->link = NULL;
+ struct hci_conn *link = conn->link;
+
+ if (link) {
+ hci_conn_unlink(conn);
/* Due to race, SCO connection might be not established
* yet at this point. Delete it now, otherwise it is
* possible for it to be stuck and can't be deleted.
*/
- if (sco->handle == HCI_CONN_HANDLE_UNSET)
- hci_conn_del(sco);
+ if (link->handle == HCI_CONN_HANDLE_UNSET)
+ hci_conn_del(link);
}

/* Unacked frames */
@@ -1104,7 +1116,7 @@ int hci_conn_del(struct hci_conn *conn)
struct hci_conn *acl = conn->link;

if (acl) {
- acl->link = NULL;
+ hci_conn_unlink(conn);
hci_conn_drop(acl);
}

@@ -2444,6 +2456,12 @@ void hci_conn_hash_flush(struct hci_dev *hdev)
c->state = BT_CLOSED;

hci_disconn_cfm(c, HCI_ERROR_LOCAL_HOST_TERM);
+
+ /* Unlink before deleting otherwise it is possible that
+ * hci_conn_del removes the link which may cause the list to
+ * contain items already freed.
+ */
+ hci_conn_unlink(c);
hci_conn_del(c);
}
}
--
2.39.2


2023-04-03 22:04:32

by bluez.test.bot

[permalink] [raw]
Subject: RE: Bluetooth: hci_conn: Fix possible UAF

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=736562

---Test result---

Test Summary:
CheckPatch PASS 0.62 seconds
GitLint PASS 0.25 seconds
SubjectPrefix PASS 0.07 seconds
BuildKernel PASS 37.55 seconds
CheckAllWarning PASS 40.54 seconds
CheckSparse PASS 46.01 seconds
CheckSmatch PASS 125.98 seconds
BuildKernel32 PASS 36.22 seconds
TestRunnerSetup PASS 516.35 seconds
TestRunner_l2cap-tester PASS 18.33 seconds
TestRunner_iso-tester PASS 18.43 seconds
TestRunner_bnep-tester PASS 6.17 seconds
TestRunner_mgmt-tester PASS 122.58 seconds
TestRunner_rfcomm-tester PASS 9.89 seconds
TestRunner_sco-tester PASS 8.88 seconds
TestRunner_ioctl-tester PASS 10.41 seconds
TestRunner_mesh-tester PASS 7.83 seconds
TestRunner_smp-tester PASS 8.90 seconds
TestRunner_userchan-tester PASS 6.45 seconds
IncrementalBuild PASS 33.86 seconds



---
Regards,
Linux Bluetooth