From: Fedor Pchelkin <pchelkin@xxxxxxxxx> commit 5c61419e02033eaf01733d66e2fcd4044808f482 upstream. One of the possible ways to enable the input MTU auto-selection for L2CAP connections is supposed to be through passing a special "0" value for it as a socket option. Commit [1] added one of those into avdtp. However, it simply wouldn't work because the kernel still treats the specified value as invalid and denies the setting attempt. Recorded BlueZ logs include the following: bluetoothd[496]: profiles/audio/avdtp.c:l2cap_connect() setsockopt(L2CAP_OPTIONS): Invalid argument (22) [1]: https://github.com/bluez/bluez/commit/ae5be371a9f53fed33d2b34748a95a5498fd4b77 Found by Linux Verification Center (linuxtesting.org). Fixes: 4b6e228e297b ("Bluetooth: Auto tune if input MTU is set to 0") Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: Fedor Pchelkin <pchelkin@xxxxxxxxx> Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/bluetooth/l2cap_sock.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/net/bluetooth/l2cap_sock.c +++ b/net/bluetooth/l2cap_sock.c @@ -727,12 +727,12 @@ static bool l2cap_valid_mtu(struct l2cap { switch (chan->scid) { case L2CAP_CID_ATT: - if (mtu < L2CAP_LE_MIN_MTU) + if (mtu && mtu < L2CAP_LE_MIN_MTU) return false; break; default: - if (mtu < L2CAP_DEFAULT_MIN_MTU) + if (mtu && mtu < L2CAP_DEFAULT_MIN_MTU) return false; } Patches currently in stable-queue which might be from pchelkin@xxxxxxxxx are queue-5.10/bluetooth-l2cap-handle-null-sock-pointer-in-l2cap_sock_alloc.patch queue-5.10/bluetooth-l2cap-accept-zero-as-a-special-value-for-mtu-auto-selection.patch
