linux.git/net/bluetooth, branch v6.18.21

Bluetooth: L2CAP: Fix regressions caused by reusing ident

2026-04-02T11:23:33+00:00

commit 761fb8ec8778f0caf2bba5a41e3cff1ea86974f3 upstream.

This attempt to fix regressions caused by reusing ident which apparently
is not handled well on certain stacks causing the stack to not respond to
requests, so instead of simple returning the first unallocated id this
stores the last used tx_ident and then attempt to use the next until all
available ids are exausted and then cycle starting over to 1.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=221120
Link: https://bugzilla.kernel.org/show_bug.cgi?id=221177
Fixes: 6c3ea155e5ee ("Bluetooth: L2CAP: Fix not tracking outstanding TX ident")
Signed-off-by: Luiz Augusto von Dentz 
Tested-by: Christian Eggers 
Signed-off-by: Greg Kroah-Hartman

Bluetooth: L2CAP: Fix ERTM re-init and zero pdu_len infinite loop

2026-04-02T11:23:09+00:00

[ Upstream commit 25f420a0d4cfd61d3d23ec4b9c56d9f443d91377 ]

l2cap_config_req() processes CONFIG_REQ for channels in BT_CONNECTED
state to support L2CAP reconfiguration (e.g. MTU changes). However,
since both CONF_INPUT_DONE and CONF_OUTPUT_DONE are already set from
the initial configuration, the reconfiguration path falls through to
l2cap_ertm_init(), which re-initializes tx_q, srej_q, srej_list, and
retrans_list without freeing the previous allocations and sets
chan->sdu to NULL without freeing the existing skb. This leaks all
previously allocated ERTM resources.

Additionally, l2cap_parse_conf_req() does not validate the minimum
value of remote_mps derived from the RFC max_pdu_size option. A zero
value propagates to l2cap_segment_sdu() where pdu_len becomes zero,
causing the while loop to never terminate since len is never
decremented, exhausting all available memory.

Fix the double-init by skipping l2cap_ertm_init() and
l2cap_chan_ready() when the channel is already in BT_CONNECTED state,
while still allowing the reconfiguration parameters to be updated
through l2cap_parse_conf_req(). Also add a pdu_len zero check in
l2cap_segment_sdu() as a safeguard.

Fixes: 96298f640104 ("Bluetooth: L2CAP: handle l2cap config request during open state")
Signed-off-by: Hyunwoo Kim 
Signed-off-by: Luiz Augusto von Dentz 
Signed-off-by: Sasha Levin

Bluetooth: L2CAP: Fix deadlock in l2cap_conn_del()

2026-04-02T11:23:09+00:00

[ Upstream commit 00fdebbbc557a2fc21321ff2eaa22fd70c078608 ]

l2cap_conn_del() calls cancel_delayed_work_sync() for both info_timer
and id_addr_timer while holding conn->lock. However, the work functions
l2cap_info_timeout() and l2cap_conn_update_id_addr() both acquire
conn->lock, creating a potential AB-BA deadlock if the work is already
executing when l2cap_conn_del() takes the lock.

Move the work cancellations before acquiring conn->lock and use
disable_delayed_work_sync() to additionally prevent the works from
being rearmed after cancellation, consistent with the pattern used in
hci_conn_del().

Fixes: ab4eedb790ca ("Bluetooth: L2CAP: Fix corrupted list in hci_chan_del")
Signed-off-by: Hyunwoo Kim 
Signed-off-by: Luiz Augusto von Dentz 
Signed-off-by: Sasha Levin

Bluetooth: L2CAP: Fix not tracking outstanding TX ident

2026-04-02T11:23:08+00:00

[ Upstream commit 6c3ea155e5ee3e56606233acde8309afda66d483 ]

This attempts to proper track outstanding request by using struct ida
and allocating from it in l2cap_get_ident using ida_alloc_range which
would reuse ids as they are free, then upon completion release
the id using ida_free.

This fixes the qualification test case L2CAP/COS/CED/BI-29-C which
attempts to check if the host stack is able to work after 256 attempts
to connect which requires Ident field to use the full range of possible
values in order to pass the test.

Link: https://github.com/bluez/bluez/issues/1829
Signed-off-by: Luiz Augusto von Dentz 
Reviewed-by: Paul Menzel 
Stable-dep-of: 00fdebbbc557 ("Bluetooth: L2CAP: Fix deadlock in l2cap_conn_del()")
Signed-off-by: Sasha Levin

Bluetooth: L2CAP: Fix send LE flow credits in ACL link

2026-04-02T11:23:08+00:00

[ Upstream commit f39f905e55f529b036321220af1ba4f4085564a5 ]

When the L2CAP channel mode is L2CAP_MODE_ERTM/L2CAP_MODE_STREAMING,
l2cap_publish_rx_avail will be called and le flow credits will be sent in
l2cap_chan_rx_avail, even though the link type is ACL.

The logs in question as follows:
> ACL Data RX: Handle 129 flags 0x02 dlen 12
      L2CAP: Unknown (0x16) ident 4 len 4
        40 00 ed 05
< ACL Data TX: Handle 129 flags 0x00 dlen 10
      L2CAP: Command Reject (0x01) ident 4 len 2
        Reason: Command not understood (0x0000)

Bluetooth: Unknown BR/EDR signaling command 0x16
Bluetooth: Wrong link type (-22)

Fixes: ce60b9231b66 ("Bluetooth: compute LE flow credits based on recvbuf space")
Signed-off-by: Zhang Chen 
Signed-off-by: Luiz Augusto von Dentz 
Signed-off-by: Sasha Levin

Bluetooth: L2CAP: Fix null-ptr-deref on l2cap_sock_ready_cb

2026-04-02T11:23:04+00:00

[ Upstream commit b6552e0503973daf6f23bd6ed9273ef131ee364f ]

Before using sk pointer, check if it is null.

Fix the following:

 KASAN: null-ptr-deref in range [0x0000000000000260-0x0000000000000267]
 CPU: 0 UID: 0 PID: 5985 Comm: kworker/0:5 Not tainted 7.0.0-rc4-00029-ga989fde763f4 #1 PREEMPT(full)
 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.17.0-9.fc43 06/10/2025
 Workqueue: events l2cap_info_timeout
 RIP: 0010:kasan_byte_accessible+0x12/0x30
 Code: 79 ff ff ff 0f 1f 40 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f 40 d6 48 c1 ef 03 48 b8 00 00 00 00 00 fc ff df <0f> b6 04 07 3c 08 0f 92 c0 c3 cc cce
 veth0_macvtap: entered promiscuous mode
 RSP: 0018:ffffc90006e0f808 EFLAGS: 00010202
 RAX: dffffc0000000000 RBX: ffffffff89746018 RCX: 0000000080000001
 RDX: 0000000000000000 RSI: ffffffff89746018 RDI: 000000000000004c
 RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000
 R10: dffffc0000000000 R11: ffffffff8aae3e70 R12: 0000000000000000
 R13: 0000000000000260 R14: 0000000000000260 R15: 0000000000000001
 FS:  0000000000000000(0000) GS:ffff8880983c2000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 00005582615a5008 CR3: 000000007007e000 CR4: 0000000000752ef0
 PKRU: 55555554
 Call Trace:
  
  __kasan_check_byte+0x12/0x40
  lock_acquire+0x79/0x2e0
  lock_sock_nested+0x48/0x100
  ? l2cap_sock_ready_cb+0x46/0x160
  l2cap_sock_ready_cb+0x46/0x160
  l2cap_conn_start+0x779/0xff0
  ? __pfx_l2cap_conn_start+0x10/0x10
  ? l2cap_info_timeout+0x60/0xa0
  ? __pfx___mutex_lock+0x10/0x10
  l2cap_info_timeout+0x68/0xa0
  ? process_scheduled_works+0xa8d/0x18c0
  process_scheduled_works+0xb6e/0x18c0
  ? __pfx_process_scheduled_works+0x10/0x10
  ? assign_work+0x3d5/0x5e0
  worker_thread+0xa53/0xfc0
  kthread+0x388/0x470
  ? __pfx_worker_thread+0x10/0x10
  ? __pfx_kthread+0x10/0x10
  ret_from_fork+0x51e/0xb90
  ? __pfx_ret_from_fork+0x10/0x10
 veth1_macvtap: entered promiscuous mode
  ? __switch_to+0xc7d/0x1450
  ? __pfx_kthread+0x10/0x10
  ret_from_fork_asm+0x1a/0x30
  
 Modules linked in:
 ---[ end trace 0000000000000000 ]---
 batman_adv: batadv0: Interface activated: batadv_slave_0
 batman_adv: batadv0: Interface activated: batadv_slave_1
 netdevsim netdevsim7 netdevsim0: set [1, 0] type 2 family 0 port 6081 - 0
 netdevsim netdevsim7 netdevsim1: set [1, 0] type 2 family 0 port 6081 - 0
 netdevsim netdevsim7 netdevsim2: set [1, 0] type 2 family 0 port 6081 - 0
 netdevsim netdevsim7 netdevsim3: set [1, 0] type 2 family 0 port 6081 - 0
 RIP: 0010:kasan_byte_accessible+0x12/0x30
 Code: 79 ff ff ff 0f 1f 40 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f 40 d6 48 c1 ef 03 48 b8 00 00 00 00 00 fc ff df <0f> b6 04 07 3c 08 0f 92 c0 c3 cc cce
 ieee80211 phy39: Selected rate control algorithm 'minstrel_ht'
 RSP: 0018:ffffc90006e0f808 EFLAGS: 00010202
 RAX: dffffc0000000000 RBX: ffffffff89746018 RCX: 0000000080000001
 RDX: 0000000000000000 RSI: ffffffff89746018 RDI: 000000000000004c
 RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000
 R10: dffffc0000000000 R11: ffffffff8aae3e70 R12: 0000000000000000
 R13: 0000000000000260 R14: 0000000000000260 R15: 0000000000000001
 FS:  0000000000000000(0000) GS:ffff8880983c2000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 00007f7e16139e9c CR3: 000000000e74e000 CR4: 0000000000752ef0
 PKRU: 55555554
 Kernel panic - not syncing: Fatal exception

Fixes: 54a59aa2b562 ("Bluetooth: Add l2cap_chan->ops->ready()")
Signed-off-by: Helen Koike 
Signed-off-by: Luiz Augusto von Dentz 
Signed-off-by: Sasha Levin

Bluetooth: MGMT: Fix dangling pointer on mgmt_add_adv_patterns_monitor_complete

2026-04-02T11:23:04+00:00

[ Upstream commit 5f5fa4cd35f707344f65ce9e225b6528691dbbaa ]

This fixes the condition checking so mgmt_pending_valid is executed
whenever status != -ECANCELED otherwise calling mgmt_pending_free(cmd)
would kfree(cmd) without unlinking it from the list first, leaving a
dangling pointer. Any subsequent list traversal (e.g.,
mgmt_pending_foreach during __mgmt_power_off, or another
mgmt_pending_valid call) would dereference freed memory.

Link: https://lore.kernel.org/linux-bluetooth/20260315132013.75ab40c5@kernel.org/T/#m1418f9c82eeff8510c1beaa21cf53af20db96c06
Fixes: 302a1f674c00 ("Bluetooth: MGMT: Fix possible UAFs")
Signed-off-by: Luiz Augusto von Dentz 
Reviewed-by: Paul Menzel 
Signed-off-by: Sasha Levin

Bluetooth: SCO: Fix use-after-free in sco_recv_frame() due to missing sock_hold

2026-04-02T11:23:04+00:00

[ Upstream commit 598dbba9919c5e36c54fe1709b557d64120cb94b ]

sco_recv_frame() reads conn->sk under sco_conn_lock() but immediately
releases the lock without holding a reference to the socket. A concurrent
close() can free the socket between the lock release and the subsequent
sk->sk_state access, resulting in a use-after-free.

Other functions in the same file (sco_sock_timeout(), sco_conn_del())
correctly use sco_sock_hold() to safely hold a reference under the lock.

Fix by using sco_sock_hold() to take a reference before releasing the
lock, and adding sock_put() on all exit paths.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Hyunwoo Kim 
Signed-off-by: Luiz Augusto von Dentz 
Signed-off-by: Sasha Levin

Bluetooth: L2CAP: Validate PDU length before reading SDU length in l2cap_ecred_data_rcv()

2026-04-02T11:23:03+00:00

[ Upstream commit c65bd945d1c08c3db756821b6bf9f1c4a77b29c6 ]

l2cap_ecred_data_rcv() reads the SDU length field from skb->data using
get_unaligned_le16() without first verifying that skb contains at least
L2CAP_SDULEN_SIZE (2) bytes. When skb->len is less than 2, this reads
past the valid data in the skb.

The ERTM reassembly path correctly calls pskb_may_pull() before reading
the SDU length (l2cap_reassemble_sdu, L2CAP_SAR_START case). Apply the
same validation to the Enhanced Credit Based Flow Control data path.

Fixes: aac23bf63659 ("Bluetooth: Implement LE L2CAP reassembly")
Signed-off-by: Hyunwoo Kim 
Signed-off-by: Luiz Augusto von Dentz 
Signed-off-by: Sasha Levin

Bluetooth: L2CAP: Fix stack-out-of-bounds read in l2cap_ecred_conn_req

2026-04-02T11:23:03+00:00

[ Upstream commit 9d87cb22195b2c67405f5485d525190747ad5493 ]

Syzbot reported a KASAN stack-out-of-bounds read in l2cap_build_cmd()
that is triggered by a malformed Enhanced Credit Based Connection Request.

The vulnerability stems from l2cap_ecred_conn_req(). The function allocates
a local stack buffer (`pdu`) designed to hold a maximum of 5 Source Channel
IDs (SCIDs), totaling 18 bytes. When an attacker sends a request with more
than 5 SCIDs, the function calculates `rsp_len` based on this unvalidated
`cmd_len` before checking if the number of SCIDs exceeds
L2CAP_ECRED_MAX_CID.

If the SCID count is too high, the function correctly jumps to the
`response` label to reject the packet, but `rsp_len` retains the
attacker's oversized value. Consequently, l2cap_send_cmd() is instructed
to read past the end of the 18-byte `pdu` buffer, triggering a
KASAN panic.

Fix this by moving the assignment of `rsp_len` to after the `num_scid`
boundary check. If the packet is rejected, `rsp_len` will safely
remain 0, and the error response will only read the 8-byte base header
from the stack.

Fixes: c28d2bff7044 ("Bluetooth: L2CAP: Fix result of L2CAP_ECRED_CONN_RSP when MTU is too short")
Reported-by: syzbot+b7f3e7d9a596bf6a63e3@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=b7f3e7d9a596bf6a63e3
Tested-by: syzbot+b7f3e7d9a596bf6a63e3@syzkaller.appspotmail.com
Signed-off-by: Minseo Park 
Signed-off-by: Luiz Augusto von Dentz 
Signed-off-by: Sasha Levin