[PATCH] Bluetooth: bnep: fix incorrect length parsing in bnep_rx_frame() extension handling

[PATCH] Bluetooth: bnep: fix incorrect length parsing in bnep_rx_frame() extension handling

[Dudu Lu]

In bnep_rx_frame(), the BNEP_FILTER_NET_TYPE_SET and
BNEP_FILTER_MULTI_ADDR_SET extension header parsing has two bugs:

1) The 2-byte length field is read with *(u16 *)(skb->data + 1), which
   performs a native-endian read. The BNEP protocol specifies this field
   in big-endian (network byte order), and the same file correctly uses
   get_unaligned_be16() for the identical fields in
   bnep_ctrl_set_netfilter() and bnep_ctrl_set_mcfilter().

2) The length is multiplied by 2, but unlike BNEP_SETUP_CONN_REQ where
   the length byte counts UUID pairs (requiring * 2 for two UUIDs per
   entry), the filter extension length field already represents the total
   data size in bytes. This is confirmed by bnep_ctrl_set_netfilter()
   which reads the same field as a byte count and divides by 4 to get
   the number of filter entries.

   The bogus * 2 means skb_pull advances twice as far as it should,
   either dropping valid data from the next header or causing the pull
   to fail entirely when the doubled length exceeds the remaining skb.

Fix by splitting the pull into two steps: first use skb_pull_data() to
safely pull and validate the 3-byte fixed header (ctrl type + length),
then pull the variable-length data using the properly decoded length.

Fixes: bf8b9a9cb77b ("Bluetooth: bnep: Add support to extended headers of control frames")
Signed-off-by: Dudu Lu <phx0fer@gmail.com>
---
 net/bluetooth/bnep/core.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/net/bluetooth/bnep/core.c b/net/bluetooth/bnep/core.c
index d44987d4515c..853c8d7644b5 100644
--- a/net/bluetooth/bnep/core.c
+++ b/net/bluetooth/bnep/core.c
@@ -330,11 +330,18 @@ static int bnep_rx_frame(struct bnep_session *s, struct sk_buff *skb)
 				goto badframe;
 			break;
 		case BNEP_FILTER_MULTI_ADDR_SET:
-		case BNEP_FILTER_NET_TYPE_SET:
-			/* Pull: ctrl type (1 b), len (2 b), data (len bytes) */
-			if (!skb_pull(skb, 3 + *(u16 *)(skb->data + 1) * 2))
+		case BNEP_FILTER_NET_TYPE_SET: {
+			u8 *hdr;
+
+			/* Pull ctrl type (1 b) + len (2 b) */
+			hdr = skb_pull_data(skb, 3);
+			if (!hdr)
+				goto badframe;
+			/* Pull data (len bytes); length is big-endian */
+			if (!skb_pull(skb, get_unaligned_be16(&hdr[1])))
 				goto badframe;
 			break;
+		}
 		default:
 			kfree_skb(skb);
 			return 0;
-- 
2.39.3 (Apple Git-145)

RE: Bluetooth: bnep: fix incorrect length parsing in bnep_rx_frame() extension handling

[bluez.test.bot]

[-- Attachment #1: Type: text/plain, Size: 7212 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=1081496

---Test result---

Test Summary:
CheckPatch                    PASS      0.54 seconds
GitLint                       FAIL      0.20 seconds
SubjectPrefix                 PASS      0.06 seconds
BuildKernel                   PASS      29.56 seconds
CheckAllWarning               PASS      28.81 seconds
CheckSparse                   PASS      27.42 seconds
BuildKernel32                 PASS      25.63 seconds
TestRunnerSetup               PASS      579.38 seconds
TestRunner_l2cap-tester       PASS      28.08 seconds
TestRunner_iso-tester         PASS      40.20 seconds
TestRunner_bnep-tester        PASS      6.45 seconds
TestRunner_mgmt-tester        FAIL      115.67 seconds
TestRunner_rfcomm-tester      PASS      9.46 seconds
TestRunner_sco-tester         FAIL      14.02 seconds
TestRunner_ioctl-tester       PASS      10.11 seconds
TestRunner_mesh-tester        FAIL      12.14 seconds
TestRunner_smp-tester         PASS      8.48 seconds
TestRunner_userchan-tester    PASS      7.82 seconds
TestRunner_6lowpan-tester     FAIL      8.30 seconds
IncrementalBuild              PASS      24.39 seconds

Details
##############################
Test: GitLint - FAIL
Desc: Run gitlint
Output:
Bluetooth: bnep: fix incorrect length parsing in bnep_rx_frame() extension handling

WARNING: I3 - ignore-body-lines: gitlint will be switching from using Python regex 'match' (match beginning) to 'search' (match anywhere) semantics. Please review your ignore-body-lines.regex option accordingly. To remove this warning, set general.regex-style-search=True. More details: https://jorisroovers.github.io/gitlint/configuration/#regex-style-search
1: T1 Title exceeds max length (83>80): "Bluetooth: bnep: fix incorrect length parsing in bnep_rx_frame() extension handling"
##############################
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       0.105 seconds
##############################
Test: TestRunner_sco-tester - FAIL
Desc: Run sco-tester with test-runner
Output:
WARNING: possible circular locking dependency detected
7.0.0-rc2-gc0f338b85a8d #1 Not tainted
------------------------------------------------------
kworker/u5:2/117 is trying to acquire lock:
ffff888001abe240 (sk_lock-AF_BLUETOOTH-BTPROTO_SCO){+.+.}-{0:0}, at: sco_connect_cfm+0x358/0x8d0

but task is already holding lock:
ffff888002094c20 (&conn->lock){+.+.}-{3:3}, at: sco_connect_cfm+0x22d/0x8d0

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&conn->lock){+.+.}-{3:3}:
       lock_acquire+0xf7/0x2c0
       _raw_spin_lock+0x2a/0x40
       sco_sock_connect+0x4d7/0x1280
       __sys_connect+0x1a3/0x260
       __x64_sys_connect+0x6e/0xb0
       do_syscall_64+0xa0/0x570
       entry_SYSCALL_64_after_hwframe+0x74/0x7c

-> #0 (sk_lock-AF_BLUETOOTH-BTPROTO_SCO){+.+.}-{0:0}:
       check_prev_add+0xe9/0xc70
       __lock_acquire+0x1457/0x1df0
       lock_acquire+0xf7/0x2c0
       lock_sock_nested+0x36/0xd0
       sco_connect_cfm+0x358/0x8d0
       hci_sync_conn_complete_evt+0x3d3/0x8e0
       hci_event_packet+0x74f/0xb10
       hci_rx_work+0x398/0xd00
       process_scheduled_works+0xb16/0x1ac0
       worker_thread+0x4ff/0xba0
       kthread+0x368/0x490
       ret_from_fork+0x498/0x7e0
       ret_from_fork_asm+0x19/0x30

other info that might help us debug this:

...
BUG: sleeping function called from invalid context at net/core/sock.c:3782
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 117, name: kworker/u5:2
preempt_count: 1, expected: 0
RCU nest depth: 0, expected: 0
INFO: lockdep is turned off.
CPU: 0 UID: 0 PID: 117 Comm: kworker/u5:2 Not tainted 7.0.0-rc2-gc0f338b85a8d #1 PREEMPT(lazy) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-1ubuntu1.1 04/01/2014
Workqueue: hci0 hci_rx_work
Call Trace:
 <TASK>
 dump_stack_lvl+0x49/0x60
 __might_resched+0x2ea/0x500
 lock_sock_nested+0x47/0xd0
 ? sco_connect_cfm+0x358/0x8d0
 sco_connect_cfm+0x358/0x8d0
 ? hci_debugfs_create_conn+0x190/0x210
 ? __pfx_sco_connect_cfm+0x10/0x10
 hci_sync_conn_complete_evt+0x3d3/0x8e0
 hci_event_packet+0x74f/0xb10
 ? __pfx_hci_sync_conn_complete_evt+0x10/0x10
 ? __pfx_hci_event_packet+0x10/0x10
 ? mark_held_locks+0x49/0x80
 ? lockdep_hardirqs_on_prepare+0xd4/0x180
 ? _raw_spin_unlock_irqrestore+0x2c/0x50
 hci_rx_work+0x398/0xd00
 process_scheduled_works+0xb16/0x1ac0
 ? __pfx_process_scheduled_works+0x10/0x10
 ? lock_acquire+0xf7/0x2c0
 ? lock_is_held_type+0x9b/0x110
 ? __pfx_hci_rx_work+0x10/0x10
 worker_thread+0x4ff/0xba0
 ? _raw_spin_unlock_irqrestore+0x2c/0x50
 ? __pfx_worker_thread+0x10/0x10
 kthread+0x368/0x490
 ? _raw_spin_unlock_irq+0x23/0x40
 ? __pfx_kthread+0x10/0x10
 ret_from_fork+0x498/0x7e0
 ? __pfx_ret_from_fork+0x10/0x10
 ? __switch_to+0x9e4/0xe50
 ? __switch_to_asm+0x32/0x60
...
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    2.672 seconds
Mesh - Send cancel - 2                               Timed out    1.991 seconds
##############################
Test: TestRunner_6lowpan-tester - FAIL
Desc: Run 6lowpan-tester with test-runner
Output:
WARNING: possible circular locking dependency detected
7.0.0-rc2-gc0f338b85a8d #1 Not tainted
------------------------------------------------------
kworker/0:1/11 is trying to acquire lock:
ffff8880026e1140 ((wq_completion)hci0#2){+.+.}-{0:0}, at: touch_wq_lockdep_map+0x75/0x180

but task is already holding lock:
ffffffffa064d720 (rtnl_mutex){+.+.}-{4:4}, at: lowpan_unregister_netdev+0xd/0x30

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #4 (rtnl_mutex){+.+.}-{4:4}:
       lock_acquire+0xf7/0x2c0
       __mutex_lock+0x16b/0x1fc0
       lowpan_register_netdev+0x11/0x30
       chan_ready_cb+0x836/0xd00
       l2cap_recv_frame+0x6a06/0x8920
       l2cap_recv_acldata+0x790/0xdf0
       hci_rx_work+0x500/0xd00
       process_scheduled_works+0xb16/0x1ac0
       worker_thread+0x4ff/0xba0
       kthread+0x368/0x490
       ret_from_fork+0x498/0x7e0
       ret_from_fork_asm+0x19/0x30

-> #3 (&chan->lock#3/1){+.+.}-{4:4}:
       lock_acquire+0xf7/0x2c0
       __mutex_lock+0x16b/0x1fc0
       l2cap_chan_connect+0x74e/0x1980
       lowpan_control_write+0x523/0x660
       full_proxy_write+0x10b/0x190
       vfs_write+0x1c0/0xf60
       ksys_write+0xf1/0x1d0
       do_syscall_64+0xa0/0x570
       entry_SYSCALL_64_after_hwframe+0x74/0x7c

-> #2 (&conn->lock){+.+.}-{4:4}:
...
Total: 8, Passed: 8 (100.0%), Failed: 0, Not Run: 0


https://github.com/bluez/bluetooth-next/pull/86

---
Regards,
Linux Bluetooth

Re: [PATCH] Bluetooth: bnep: fix incorrect length parsing in bnep_rx_frame() extension handling

[patchwork-bot+bluetooth]

Hello:

This patch was applied to bluetooth/bluetooth-next.git (master)
by Luiz Augusto von Dentz <luiz.von.dentz@intel.com>:

On Wed, 15 Apr 2026 17:39:53 +0800 you wrote:
> In bnep_rx_frame(), the BNEP_FILTER_NET_TYPE_SET and
> BNEP_FILTER_MULTI_ADDR_SET extension header parsing has two bugs:
> 
> 1) The 2-byte length field is read with *(u16 *)(skb->data + 1), which
>    performs a native-endian read. The BNEP protocol specifies this field
>    in big-endian (network byte order), and the same file correctly uses
>    get_unaligned_be16() for the identical fields in
>    bnep_ctrl_set_netfilter() and bnep_ctrl_set_mcfilter().
> 
> [...]

Here is the summary with links:
  - Bluetooth: bnep: fix incorrect length parsing in bnep_rx_frame() extension handling
    https://git.kernel.org/bluetooth/bluetooth-next/c/5843e5ef062a

You are awesome, thank you!
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