From: Fedor Pchelkin Date: Tue, 28 Jan 2025 21:08:14 +0000 (+0300) Subject: Bluetooth: L2CAP: accept zero as a special value for MTU auto-selection X-Git-Tag: v6.14-rc1~33^2~6^2 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=5c61419e02033eaf01733d66e2fcd4044808f482;p=thirdparty%2Fkernel%2Flinux.git Bluetooth: L2CAP: accept zero as a special value for MTU auto-selection 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@vger.kernel.org Signed-off-by: Fedor Pchelkin Signed-off-by: Luiz Augusto von Dentz --- diff --git a/net/bluetooth/l2cap_sock.c b/net/bluetooth/l2cap_sock.c index 49f97d4138ea7..46ea0bee2259f 100644 --- a/net/bluetooth/l2cap_sock.c +++ b/net/bluetooth/l2cap_sock.c @@ -710,12 +710,12 @@ static bool l2cap_valid_mtu(struct l2cap_chan *chan, u16 mtu) { 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; }