From: Luiz Augusto von Dentz luiz.von.dentz@intel.com

L2CAP_OPTIONS shall only be used with BR/EDR modes.

Signed-off-by: Luiz Augusto von Dentz luiz.von.dentz@intel.com Signed-off-by: Marcel Holtmann marcel@holtmann.org (cherry picked from commit b86b0b150fed840c376145383ef5105116c81b0c) Signed-off-by: Zubin Mithra zsm@chromium.org --- * Syzkaller triggered a GPF with the following stacktrace: l2cap_chan_send+0xa6e/0x1c30 net/bluetooth/l2cap_core.c:2532 l2cap_sock_sendmsg+0x1da/0x1fd net/bluetooth/l2cap_sock.c:985 sock_sendmsg_nosec+0x88/0xb4 net/socket.c:638 sock_sendmsg+0x5e/0x6f net/socket.c:658 ____sys_sendmsg+0x45c/0x5a5 net/socket.c:2298 ___sys_sendmsg+0x13e/0x19f net/socket.c:2352 __sys_sendmmsg+0x298/0x38c net/socket.c:2455 __do_sys_sendmmsg net/socket.c:2484 [inline] __se_sys_sendmmsg net/socket.c:2481 [inline] __x64_sys_sendmmsg+0xad/0xb6 net/socket.c:2481 do_syscall_64+0x10b/0x144 arch/x86/entry/common.c:299 entry_SYSCALL_64_after_hwframe+0x49/0xbe

* This commit is present in 5.10.y and newer. 4.19.y and older do not need this fix.

* This patch resolves conflicts that arise due to a BT_DBG() introduced in the following commit not being present in linux-5.4.y: - 15f02b910562 ("Bluetooth: L2CAP: Add initial code for Enhanced Credit Based Mode")

* Tests run: syzkaller reproducer, Chrome OS tryjobs

net/bluetooth/l2cap_sock.c | 24 ++++++++++++++++++++---- 1 file changed, 20 insertions(+), 4 deletions(-)

diff --git a/net/bluetooth/l2cap_sock.c b/net/bluetooth/l2cap_sock.c index 8648c5211ebe..e43da778c993 100644 --- a/net/bluetooth/l2cap_sock.c +++ b/net/bluetooth/l2cap_sock.c @@ -418,6 +418,20 @@ static int l2cap_sock_getsockopt_old(struct socket *sock, int optname, break; }

+ /* Only BR/EDR modes are supported here */ + switch (chan->mode) { + case L2CAP_MODE_BASIC: + case L2CAP_MODE_ERTM: + case L2CAP_MODE_STREAMING: + break; + default: + err = -EINVAL; + break; + } + + if (err < 0) + break; + memset(&opts, 0, sizeof(opts)); opts.imtu = chan->imtu; opts.omtu = chan->omtu; @@ -677,10 +691,8 @@ static int l2cap_sock_setsockopt_old(struct socket *sock, int optname, break; }

- chan->mode = opts.mode; - switch (chan->mode) { - case L2CAP_MODE_LE_FLOWCTL: - break; + /* Only BR/EDR modes are supported here */ + switch (opts.mode) { case L2CAP_MODE_BASIC: clear_bit(CONF_STATE2_DEVICE, &chan->conf_state); break; @@ -694,6 +706,10 @@ static int l2cap_sock_setsockopt_old(struct socket *sock, int optname, break; }

+ if (err < 0) + break; + + chan->mode = opts.mode; chan->imtu = opts.imtu; chan->omtu = opts.omtu; chan->fcs = opts.fcs;