linux-stable.git/net/bluetooth, branch v5.4.296

Bluetooth: L2CAP: Fix L2CAP MTU negotiation

2025-07-17T16:24:54+00:00

commit 042bb9603c44620dce98717a2d23235ca57a00d7 upstream.

OBEX download from iPhone is currently slow due to small packet size
used to transfer data which doesn't follow the MTU negotiated during
L2CAP connection, i.e. 672 bytes instead of 32767:

  < ACL Data TX: Handle 11 flags 0x00 dlen 12
      L2CAP: Connection Request (0x02) ident 18 len 4
        PSM: 4103 (0x1007)
        Source CID: 72
  > ACL Data RX: Handle 11 flags 0x02 dlen 16
      L2CAP: Connection Response (0x03) ident 18 len 8
        Destination CID: 14608
        Source CID: 72
        Result: Connection successful (0x0000)
        Status: No further information available (0x0000)
  < ACL Data TX: Handle 11 flags 0x00 dlen 27
      L2CAP: Configure Request (0x04) ident 20 len 19
        Destination CID: 14608
        Flags: 0x0000
        Option: Maximum Transmission Unit (0x01) [mandatory]
          MTU: 32767
        Option: Retransmission and Flow Control (0x04) [mandatory]
          Mode: Enhanced Retransmission (0x03)
          TX window size: 63
          Max transmit: 3
          Retransmission timeout: 2000
          Monitor timeout: 12000
          Maximum PDU size: 1009
  > ACL Data RX: Handle 11 flags 0x02 dlen 26
      L2CAP: Configure Request (0x04) ident 72 len 18
        Destination CID: 72
        Flags: 0x0000
        Option: Retransmission and Flow Control (0x04) [mandatory]
          Mode: Enhanced Retransmission (0x03)
          TX window size: 32
          Max transmit: 255
          Retransmission timeout: 0
          Monitor timeout: 0
          Maximum PDU size: 65527
        Option: Frame Check Sequence (0x05) [mandatory]
          FCS: 16-bit FCS (0x01)
  < ACL Data TX: Handle 11 flags 0x00 dlen 29
      L2CAP: Configure Response (0x05) ident 72 len 21
        Source CID: 14608
        Flags: 0x0000
        Result: Success (0x0000)
        Option: Maximum Transmission Unit (0x01) [mandatory]
          MTU: 672
        Option: Retransmission and Flow Control (0x04) [mandatory]
          Mode: Enhanced Retransmission (0x03)
          TX window size: 32
          Max transmit: 255
          Retransmission timeout: 2000
          Monitor timeout: 12000
          Maximum PDU size: 1009
  > ACL Data RX: Handle 11 flags 0x02 dlen 32
      L2CAP: Configure Response (0x05) ident 20 len 24
        Source CID: 72
        Flags: 0x0000
        Result: Success (0x0000)
        Option: Maximum Transmission Unit (0x01) [mandatory]
          MTU: 32767
        Option: Retransmission and Flow Control (0x04) [mandatory]
          Mode: Enhanced Retransmission (0x03)
          TX window size: 63
          Max transmit: 3
          Retransmission timeout: 2000
          Monitor timeout: 12000
          Maximum PDU size: 1009
        Option: Frame Check Sequence (0x05) [mandatory]
          FCS: 16-bit FCS (0x01)
  ...
  > ACL Data RX: Handle 11 flags 0x02 dlen 680
      Channel: 72 len 676 ctrl 0x0202 [PSM 4103 mode Enhanced Retransmission (0x03)] {chan 8}
      I-frame: Unsegmented TxSeq 1 ReqSeq 2
  < ACL Data TX: Handle 11 flags 0x00 dlen 13
      Channel: 14608 len 9 ctrl 0x0204 [PSM 4103 mode Enhanced Retransmission (0x03)] {chan 8}
      I-frame: Unsegmented TxSeq 2 ReqSeq 2
  > ACL Data RX: Handle 11 flags 0x02 dlen 680
      Channel: 72 len 676 ctrl 0x0304 [PSM 4103 mode Enhanced Retransmission (0x03)] {chan 8}
      I-frame: Unsegmented TxSeq 2 ReqSeq 3

The MTUs are negotiated for each direction. In this traces 32767 for
iPhone->localhost and no MTU for localhost->iPhone, which based on
'4.4 L2CAP_CONFIGURATION_REQ' (Core specification v5.4, Vol. 3, Part
A):

  The only parameters that should be included in the
  L2CAP_CONFIGURATION_REQ packet are those that require different
  values than the default or previously agreed values.
  ...
  Any missing configuration parameters are assumed to have their
  most recently explicitly or implicitly accepted values.

and '5.1 Maximum transmission unit (MTU)':

  If the remote device sends a positive L2CAP_CONFIGURATION_RSP
  packet it should include the actual MTU to be used on this channel
  for traffic flowing into the local device.
  ...
  The default value is 672 octets.

is set by BlueZ to 672 bytes.

It seems that the iPhone used the lowest negotiated value to transfer
data to the localhost instead of the negotiated one for the incoming
direction.

This could be fixed by using the MTU negotiated for the other
direction, if exists, in the L2CAP_CONFIGURATION_RSP.
This allows to use segmented packets as in the following traces:

  < ACL Data TX: Handle 11 flags 0x00 dlen 12
        L2CAP: Connection Request (0x02) ident 22 len 4
          PSM: 4103 (0x1007)
          Source CID: 72
  < ACL Data TX: Handle 11 flags 0x00 dlen 27
        L2CAP: Configure Request (0x04) ident 24 len 19
          Destination CID: 2832
          Flags: 0x0000
          Option: Maximum Transmission Unit (0x01) [mandatory]
            MTU: 32767
          Option: Retransmission and Flow Control (0x04) [mandatory]
            Mode: Enhanced Retransmission (0x03)
            TX window size: 63
            Max transmit: 3
            Retransmission timeout: 2000
            Monitor timeout: 12000
            Maximum PDU size: 1009
  > ACL Data RX: Handle 11 flags 0x02 dlen 26
        L2CAP: Configure Request (0x04) ident 15 len 18
          Destination CID: 72
          Flags: 0x0000
          Option: Retransmission and Flow Control (0x04) [mandatory]
            Mode: Enhanced Retransmission (0x03)
            TX window size: 32
            Max transmit: 255
            Retransmission timeout: 0
            Monitor timeout: 0
            Maximum PDU size: 65527
          Option: Frame Check Sequence (0x05) [mandatory]
            FCS: 16-bit FCS (0x01)
  < ACL Data TX: Handle 11 flags 0x00 dlen 29
        L2CAP: Configure Response (0x05) ident 15 len 21
          Source CID: 2832
          Flags: 0x0000
          Result: Success (0x0000)
          Option: Maximum Transmission Unit (0x01) [mandatory]
            MTU: 32767
          Option: Retransmission and Flow Control (0x04) [mandatory]
            Mode: Enhanced Retransmission (0x03)
            TX window size: 32
            Max transmit: 255
            Retransmission timeout: 2000
            Monitor timeout: 12000
            Maximum PDU size: 1009
  > ACL Data RX: Handle 11 flags 0x02 dlen 32
        L2CAP: Configure Response (0x05) ident 24 len 24
          Source CID: 72
          Flags: 0x0000
          Result: Success (0x0000)
          Option: Maximum Transmission Unit (0x01) [mandatory]
            MTU: 32767
          Option: Retransmission and Flow Control (0x04) [mandatory]
            Mode: Enhanced Retransmission (0x03)
            TX window size: 63
            Max transmit: 3
            Retransmission timeout: 2000
            Monitor timeout: 12000
            Maximum PDU size: 1009
          Option: Frame Check Sequence (0x05) [mandatory]
            FCS: 16-bit FCS (0x01)
  ...
  > ACL Data RX: Handle 11 flags 0x02 dlen 1009
        Channel: 72 len 1005 ctrl 0x4202 [PSM 4103 mode Enhanced Retransmission (0x03)] {chan 8}
        I-frame: Start (len 21884) TxSeq 1 ReqSeq 2
  > ACL Data RX: Handle 11 flags 0x02 dlen 1009
        Channel: 72 len 1005 ctrl 0xc204 [PSM 4103 mode Enhanced Retransmission (0x03)] {chan 8}
        I-frame: Continuation TxSeq 2 ReqSeq 2

This has been tested with kernel 5.4 and BlueZ 5.77.

Cc: stable@vger.kernel.org
Signed-off-by: Frédéric Danis 
Signed-off-by: Luiz Augusto von Dentz 
Signed-off-by: Greg Kroah-Hartman

Bluetooth: L2CAP: Fix not responding with L2CAP_CR_LE_ENCRYPTION

2025-06-27T10:02:49+00:00

[ Upstream commit 03dba9cea72f977e873e4e60e220fa596959dd8f ]

Depending on the security set the response to L2CAP_LE_CONN_REQ shall be
just L2CAP_CR_LE_ENCRYPTION if only encryption when BT_SECURITY_MEDIUM
is selected since that means security mode 2 which doesn't require
authentication which is something that is covered in the qualification
test L2CAP/LE/CFC/BV-25-C.

Link: https://github.com/bluez/bluez/issues/1270
Fixes: 27e2d4c8d28b ("Bluetooth: Add basic LE L2CAP connect request receiving support")
Signed-off-by: Luiz Augusto von Dentz 
Signed-off-by: Sasha Levin

Bluetooth: hci_event: Fix sending MGMT_EV_DEVICE_FOUND for invalid address

2025-05-02T05:39:19+00:00

[ Upstream commit eb73b5a9157221f405b4fe32751da84ee46b7a25 ]

This fixes sending MGMT_EV_DEVICE_FOUND for invalid address
(00:00:00:00:00:00) which is a regression introduced by
a2ec905d1e16 ("Bluetooth: fix kernel oops in store_pending_adv_report")
since in the attempt to skip storing data for extended advertisement it
actually made the code to skip the entire if statement supposed to send
MGMT_EV_DEVICE_FOUND without attempting to use the last_addr_adv which
is garanteed to be invalid for extended advertisement since we never
store anything on it.

Link: https://github.com/bluez/bluez/issues/1157
Link: https://github.com/bluez/bluez/issues/1149#issuecomment-2767215658
Fixes: a2ec905d1e16 ("Bluetooth: fix kernel oops in store_pending_adv_report")
Signed-off-by: Luiz Augusto von Dentz 
Signed-off-by: Sasha Levin

Bluetooth: Fix error code in chan_alloc_skb_cb()

2025-04-10T12:29:38+00:00

[ Upstream commit 72d061ee630d0dbb45c2920d8d19b3861c413e54 ]

The chan_alloc_skb_cb() function is supposed to return error pointers on
error.  Returning NULL will lead to a NULL dereference.

Fixes: 6b8d4a6a0314 ("Bluetooth: 6LoWPAN: Use connected oriented channel instead of fixed one")
Signed-off-by: Dan Carpenter 
Signed-off-by: Luiz Augusto von Dentz 
Signed-off-by: Sasha Levin

Bluetooth: L2CAP: handle NULL sock pointer in l2cap_sock_alloc

2025-03-13T11:43:07+00:00

commit 5f397409f8ee5bc82901eeaf799e1cbc4f8edcf1 upstream.

A NULL sock pointer is passed into l2cap_sock_alloc() when it is called
from l2cap_sock_new_connection_cb() and the error handling paths should
also be aware of it.

Seemingly a more elegant solution would be to swap bt_sock_alloc() and
l2cap_chan_create() calls since they are not interdependent to that moment
but then l2cap_chan_create() adds the soon to be deallocated and still
dummy-initialized channel to the global list accessible by many L2CAP
paths. The channel would be removed from the list in short period of time
but be a bit more straight-forward here and just check for NULL instead of
changing the order of function calls.

Found by Linux Verification Center (linuxtesting.org) with SVACE static
analysis tool.

Fixes: 7c4f78cdb8e7 ("Bluetooth: L2CAP: do not leave dangling sk pointer on error in l2cap_sock_create()")
Cc: stable@vger.kernel.org
Signed-off-by: Fedor Pchelkin 
Reviewed-by: Kuniyuki Iwashima 
Signed-off-by: Luiz Augusto von Dentz 
Signed-off-by: Greg Kroah-Hartman

Bluetooth: L2CAP: do not leave dangling sk pointer on error in l2cap_sock_create()

2024-12-14T18:44:51+00:00

[ Upstream commit 7c4f78cdb8e7501e9f92d291a7d956591bf73be9 ]

bt_sock_alloc() allocates the sk object and attaches it to the provided
sock object. On error l2cap_sock_alloc() frees the sk object, but the
dangling pointer is still attached to the sock object, which may create
use-after-free in other code.

Signed-off-by: Ignat Korchagin 
Reviewed-by: Kuniyuki Iwashima 
Reviewed-by: Eric Dumazet 
Link: https://patch.msgid.link/20241014153808.51894-3-ignat@cloudflare.com
Signed-off-by: Jakub Kicinski 
Signed-off-by: Sasha Levin

Bluetooth: Fix type of len in rfcomm_sock_getsockopt{,_old}()

2024-12-14T18:44:36+00:00

commit 5fe6caa62b07fd39cd6a28acc8f92ba2955e11a6 upstream.

Commit 9bf4e919ccad worked around an issue introduced after an innocuous
optimisation change in LLVM main:

> len is defined as an 'int' because it is assigned from
> '__user int *optlen'. However, it is clamped against the result of
> sizeof(), which has a type of 'size_t' ('unsigned long' for 64-bit
> platforms). This is done with min_t() because min() requires compatible
> types, which results in both len and the result of sizeof() being casted
> to 'unsigned int', meaning len changes signs and the result of sizeof()
> is truncated. From there, len is passed to copy_to_user(), which has a
> third parameter type of 'unsigned long', so it is widened and changes
> signs again. This excessive casting in combination with the KCSAN
> instrumentation causes LLVM to fail to eliminate the __bad_copy_from()
> call, failing the build.

The same issue occurs in rfcomm in functions rfcomm_sock_getsockopt and
rfcomm_sock_getsockopt_old.

Change the type of len to size_t in both rfcomm_sock_getsockopt and
rfcomm_sock_getsockopt_old and replace min_t() with min().

Cc: stable@vger.kernel.org
Co-authored-by: Aleksei Vetrov 
Improves: 9bf4e919ccad ("Bluetooth: Fix type of len in {l2cap,sco}_sock_getsockopt_old()")
Link: https://github.com/ClangBuiltLinux/linux/issues/2007
Link: https://github.com/llvm/llvm-project/issues/85647
Signed-off-by: Andrej Shadura 
Reviewed-by: Nathan Chancellor 
Signed-off-by: Luiz Augusto von Dentz 
Signed-off-by: Greg Kroah-Hartman

Bluetooth: bnep: fix wild-memory-access in proto_unregister

2024-11-08T15:20:50+00:00

[ Upstream commit 64a90991ba8d4e32e3173ddd83d0b24167a5668c ]

There's issue as follows:
  KASAN: maybe wild-memory-access in range [0xdead...108-0xdead...10f]
  CPU: 3 UID: 0 PID: 2805 Comm: rmmod Tainted: G        W
  RIP: 0010:proto_unregister+0xee/0x400
  Call Trace:
   
   __do_sys_delete_module+0x318/0x580
   do_syscall_64+0xc1/0x1d0
   entry_SYSCALL_64_after_hwframe+0x77/0x7f

As bnep_init() ignore bnep_sock_init()'s return value, and bnep_sock_init()
will cleanup all resource. Then when remove bnep module will call
bnep_sock_cleanup() to cleanup sock's resource.
To solve above issue just return bnep_sock_init()'s return value in
bnep_exit().

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

Bluetooth: Remove debugfs directory on module init failure

2024-11-08T15:20:48+00:00

commit 1db4564f101b47188c1b71696bd342ef09172b22 upstream.

If bt_init() fails, the debugfs directory currently is not removed. If
the module is loaded again after that, the debugfs directory is not set
up properly due to the existing directory.

  # modprobe bluetooth
  # ls -laF /sys/kernel/debug/bluetooth
  total 0
  drwxr-xr-x  2 root root 0 Sep 27 14:26 ./
  drwx------ 31 root root 0 Sep 27 14:25 ../
  -r--r--r--  1 root root 0 Sep 27 14:26 l2cap
  -r--r--r--  1 root root 0 Sep 27 14:26 sco
  # modprobe -r bluetooth
  # ls -laF /sys/kernel/debug/bluetooth
  ls: cannot access '/sys/kernel/debug/bluetooth': No such file or directory
  #

  # modprobe bluetooth
  modprobe: ERROR: could not insert 'bluetooth': Invalid argument
  # dmesg | tail -n 6
  Bluetooth: Core ver 2.22
  NET: Registered PF_BLUETOOTH protocol family
  Bluetooth: HCI device and connection manager initialized
  Bluetooth: HCI socket layer initialized
  Bluetooth: Faking l2cap_init() failure for testing
  NET: Unregistered PF_BLUETOOTH protocol family
  # ls -laF /sys/kernel/debug/bluetooth
  total 0
  drwxr-xr-x  2 root root 0 Sep 27 14:31 ./
  drwx------ 31 root root 0 Sep 27 14:26 ../
  #

  # modprobe bluetooth
  # dmesg | tail -n 7
  Bluetooth: Core ver 2.22
  debugfs: Directory 'bluetooth' with parent '/' already present!
  NET: Registered PF_BLUETOOTH protocol family
  Bluetooth: HCI device and connection manager initialized
  Bluetooth: HCI socket layer initialized
  Bluetooth: L2CAP socket layer initialized
  Bluetooth: SCO socket layer initialized
  # ls -laF /sys/kernel/debug/bluetooth
  total 0
  drwxr-xr-x  2 root root 0 Sep 27 14:31 ./
  drwx------ 31 root root 0 Sep 27 14:26 ../
  #

Cc: stable@vger.kernel.org
Fixes: ffcecac6a738 ("Bluetooth: Create root debugfs directory during module init")
Signed-off-by: Aaron Thompson 
Signed-off-by: Luiz Augusto von Dentz 
Signed-off-by: Greg Kroah-Hartman

Bluetooth: RFCOMM: FIX possible deadlock in rfcomm_sk_state_change

2024-11-08T15:20:45+00:00

[ Upstream commit 08d1914293dae38350b8088980e59fbc699a72fe ]

rfcomm_sk_state_change attempts to use sock_lock so it must never be
called with it locked but rfcomm_sock_ioctl always attempt to lock it
causing the following trace:

======================================================
WARNING: possible circular locking dependency detected
6.8.0-syzkaller-08951-gfe46a7dd189e #0 Not tainted
------------------------------------------------------
syz-executor386/5093 is trying to acquire lock:
ffff88807c396258 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1671 [inline]
ffff88807c396258 (sk_lock-AF_BLUETOOTH-BTPROTO_RFCOMM){+.+.}-{0:0}, at: rfcomm_sk_state_change+0x5b/0x310 net/bluetooth/rfcomm/sock.c:73

but task is already holding lock:
ffff88807badfd28 (&d->lock){+.+.}-{3:3}, at: __rfcomm_dlc_close+0x226/0x6a0 net/bluetooth/rfcomm/core.c:491

Reported-by: syzbot+d7ce59b06b3eb14fd218@syzkaller.appspotmail.com
Tested-by: syzbot+d7ce59b06b3eb14fd218@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=d7ce59b06b3eb14fd218
Fixes: 3241ad820dbb ("[Bluetooth] Add timestamp support to L2CAP, RFCOMM and SCO")
Signed-off-by: Luiz Augusto von Dentz 
Signed-off-by: Sasha Levin