6.6-stable review patch. If anyone has any objections, please let me know.

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From: Edward Adam Davis eadavis@qq.com

[ Upstream commit 89bb613511cc21ed5ba6bddc1c9b9ae9c0dad392 ]

There is a potential race condition between sock bind and socket write iter. bind may free the same cmd via mgmt_pending before write iter sends the cmd, just as syzbot reported in UAF[1].

Here we use hci_dev_lock to synchronize the two, thereby avoiding the UAF mentioned in [1].

[1] syzbot reported: BUG: KASAN: slab-use-after-free in mgmt_pending_remove+0x3b/0x210 net/bluetooth/mgmt_util.c:316 Read of size 8 at addr ffff888077164818 by task syz.0.17/5989 Call Trace: mgmt_pending_remove+0x3b/0x210 net/bluetooth/mgmt_util.c:316 set_link_security+0x5c2/0x710 net/bluetooth/mgmt.c:1918 hci_mgmt_cmd+0x9c9/0xef0 net/bluetooth/hci_sock.c:1719 hci_sock_sendmsg+0x6ca/0xef0 net/bluetooth/hci_sock.c:1839 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg+0x21c/0x270 net/socket.c:742 sock_write_iter+0x279/0x360 net/socket.c:1195

Allocated by task 5989: mgmt_pending_add+0x35/0x140 net/bluetooth/mgmt_util.c:296 set_link_security+0x557/0x710 net/bluetooth/mgmt.c:1910 hci_mgmt_cmd+0x9c9/0xef0 net/bluetooth/hci_sock.c:1719 hci_sock_sendmsg+0x6ca/0xef0 net/bluetooth/hci_sock.c:1839 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg+0x21c/0x270 net/socket.c:742 sock_write_iter+0x279/0x360 net/socket.c:1195

Freed by task 5991: mgmt_pending_free net/bluetooth/mgmt_util.c:311 [inline] mgmt_pending_foreach+0x30d/0x380 net/bluetooth/mgmt_util.c:257 mgmt_index_removed+0x112/0x2f0 net/bluetooth/mgmt.c:9477 hci_sock_bind+0xbe9/0x1000 net/bluetooth/hci_sock.c:1314

Fixes: 6fe26f694c82 ("Bluetooth: MGMT: Protect mgmt_pending list with its own lock") Reported-by: syzbot+9aa47cd4633a3cf92a80@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=9aa47cd4633a3cf92a80 Tested-by: syzbot+9aa47cd4633a3cf92a80@syzkaller.appspotmail.com Signed-off-by: Edward Adam Davis eadavis@qq.com Signed-off-by: Luiz Augusto von Dentz luiz.von.dentz@intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- net/bluetooth/hci_sock.c | 2 ++ 1 file changed, 2 insertions(+)

diff --git a/net/bluetooth/hci_sock.c b/net/bluetooth/hci_sock.c index d2613bd3e6db0..8b3ef088ed14e 100644 --- a/net/bluetooth/hci_sock.c +++ b/net/bluetooth/hci_sock.c @@ -1304,7 +1304,9 @@ static int hci_sock_bind(struct socket *sock, struct sockaddr *addr, goto done; }

+ hci_dev_lock(hdev); mgmt_index_removed(hdev); + hci_dev_unlock(hdev);

err = hci_dev_open(hdev->id); if (err) {