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[v5.4.y] Bluetooth: L2CAP: Fix handling LE modes by L2CAP_OPTIONS

Message ID 20210519175210.596822-1-zsm@chromium.org
State Superseded
Headers show
Series [v5.4.y] Bluetooth: L2CAP: Fix handling LE modes by L2CAP_OPTIONS | expand

Commit Message

Zubin Mithra May 19, 2021, 5:52 p.m. UTC 
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 mbox series

Patch

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;