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authorMatias Karhumaa <matias.karhumaa@gmail.com>2019-05-21 13:07:22 +0300
committerMarcel Holtmann <marcel@holtmann.org>2019-07-06 15:23:10 +0200
commit28261da8a26f4915aa257d12d506c6ba179d961f (patch)
treeb997c0eb781dfe5555aaa6f1fbe9c2c0d8b34e8b /include/net
parentBluetooth: hidp: NUL terminate a string in the compat ioctl (diff)
downloadlinux-dev-28261da8a26f4915aa257d12d506c6ba179d961f.tar.xz
linux-dev-28261da8a26f4915aa257d12d506c6ba179d961f.zip
Bluetooth: Check state in l2cap_disconnect_rsp
Because of both sides doing L2CAP disconnection at the same time, it was possible to receive L2CAP Disconnection Response with CID that was already freed. That caused problems if CID was already reused and L2CAP Connection Request with same CID was sent out. Before this patch kernel deleted channel context regardless of the state of the channel. Example where leftover Disconnection Response (frame #402) causes local device to delete L2CAP channel which was not yet connected. This in turn confuses remote device's stack because same CID is re-used without properly disconnecting. Btmon capture before patch: ** snip ** > ACL Data RX: Handle 43 flags 0x02 dlen 8 #394 [hci1] 10.748949 Channel: 65 len 4 [PSM 3 mode 0] {chan 2} RFCOMM: Disconnect (DISC) (0x43) Address: 0x03 cr 1 dlci 0x00 Control: 0x53 poll/final 1 Length: 0 FCS: 0xfd < ACL Data TX: Handle 43 flags 0x00 dlen 8 #395 [hci1] 10.749062 Channel: 65 len 4 [PSM 3 mode 0] {chan 2} RFCOMM: Unnumbered Ack (UA) (0x63) Address: 0x03 cr 1 dlci 0x00 Control: 0x73 poll/final 1 Length: 0 FCS: 0xd7 < ACL Data TX: Handle 43 flags 0x00 dlen 12 #396 [hci1] 10.749073 L2CAP: Disconnection Request (0x06) ident 17 len 4 Destination CID: 65 Source CID: 65 > HCI Event: Number of Completed Packets (0x13) plen 5 #397 [hci1] 10.752391 Num handles: 1 Handle: 43 Count: 1 > HCI Event: Number of Completed Packets (0x13) plen 5 #398 [hci1] 10.753394 Num handles: 1 Handle: 43 Count: 1 > ACL Data RX: Handle 43 flags 0x02 dlen 12 #399 [hci1] 10.756499 L2CAP: Disconnection Request (0x06) ident 26 len 4 Destination CID: 65 Source CID: 65 < ACL Data TX: Handle 43 flags 0x00 dlen 12 #400 [hci1] 10.756548 L2CAP: Disconnection Response (0x07) ident 26 len 4 Destination CID: 65 Source CID: 65 < ACL Data TX: Handle 43 flags 0x00 dlen 12 #401 [hci1] 10.757459 L2CAP: Connection Request (0x02) ident 18 len 4 PSM: 1 (0x0001) Source CID: 65 > ACL Data RX: Handle 43 flags 0x02 dlen 12 #402 [hci1] 10.759148 L2CAP: Disconnection Response (0x07) ident 17 len 4 Destination CID: 65 Source CID: 65 = bluetoothd: 00:1E:AB:4C:56:54: error updating services: Input/o.. 10.759447 > HCI Event: Number of Completed Packets (0x13) plen 5 #403 [hci1] 10.759386 Num handles: 1 Handle: 43 Count: 1 > ACL Data RX: Handle 43 flags 0x02 dlen 12 #404 [hci1] 10.760397 L2CAP: Connection Request (0x02) ident 27 len 4 PSM: 3 (0x0003) Source CID: 65 < ACL Data TX: Handle 43 flags 0x00 dlen 16 #405 [hci1] 10.760441 L2CAP: Connection Response (0x03) ident 27 len 8 Destination CID: 65 Source CID: 65 Result: Connection successful (0x0000) Status: No further information available (0x0000) < ACL Data TX: Handle 43 flags 0x00 dlen 27 #406 [hci1] 10.760449 L2CAP: Configure Request (0x04) ident 19 len 19 Destination CID: 65 Flags: 0x0000 Option: Maximum Transmission Unit (0x01) [mandatory] MTU: 1013 Option: Retransmission and Flow Control (0x04) [mandatory] Mode: Basic (0x00) TX window size: 0 Max transmit: 0 Retransmission timeout: 0 Monitor timeout: 0 Maximum PDU size: 0 > HCI Event: Number of Completed Packets (0x13) plen 5 #407 [hci1] 10.761399 Num handles: 1 Handle: 43 Count: 1 > ACL Data RX: Handle 43 flags 0x02 dlen 16 #408 [hci1] 10.762942 L2CAP: Connection Response (0x03) ident 18 len 8 Destination CID: 66 Source CID: 65 Result: Connection successful (0x0000) Status: No further information available (0x0000) *snip* Similar case after the patch: *snip* > ACL Data RX: Handle 43 flags 0x02 dlen 8 #22702 [hci0] 1664.411056 Channel: 65 len 4 [PSM 3 mode 0] {chan 3} RFCOMM: Disconnect (DISC) (0x43) Address: 0x03 cr 1 dlci 0x00 Control: 0x53 poll/final 1 Length: 0 FCS: 0xfd < ACL Data TX: Handle 43 flags 0x00 dlen 8 #22703 [hci0] 1664.411136 Channel: 65 len 4 [PSM 3 mode 0] {chan 3} RFCOMM: Unnumbered Ack (UA) (0x63) Address: 0x03 cr 1 dlci 0x00 Control: 0x73 poll/final 1 Length: 0 FCS: 0xd7 < ACL Data TX: Handle 43 flags 0x00 dlen 12 #22704 [hci0] 1664.411143 L2CAP: Disconnection Request (0x06) ident 11 len 4 Destination CID: 65 Source CID: 65 > HCI Event: Number of Completed Pac.. (0x13) plen 5 #22705 [hci0] 1664.414009 Num handles: 1 Handle: 43 Count: 1 > HCI Event: Number of Completed Pac.. (0x13) plen 5 #22706 [hci0] 1664.415007 Num handles: 1 Handle: 43 Count: 1 > ACL Data RX: Handle 43 flags 0x02 dlen 12 #22707 [hci0] 1664.418674 L2CAP: Disconnection Request (0x06) ident 17 len 4 Destination CID: 65 Source CID: 65 < ACL Data TX: Handle 43 flags 0x00 dlen 12 #22708 [hci0] 1664.418762 L2CAP: Disconnection Response (0x07) ident 17 len 4 Destination CID: 65 Source CID: 65 < ACL Data TX: Handle 43 flags 0x00 dlen 12 #22709 [hci0] 1664.421073 L2CAP: Connection Request (0x02) ident 12 len 4 PSM: 1 (0x0001) Source CID: 65 > ACL Data RX: Handle 43 flags 0x02 dlen 12 #22710 [hci0] 1664.421371 L2CAP: Disconnection Response (0x07) ident 11 len 4 Destination CID: 65 Source CID: 65 > HCI Event: Number of Completed Pac.. (0x13) plen 5 #22711 [hci0] 1664.424082 Num handles: 1 Handle: 43 Count: 1 > HCI Event: Number of Completed Pac.. (0x13) plen 5 #22712 [hci0] 1664.425040 Num handles: 1 Handle: 43 Count: 1 > ACL Data RX: Handle 43 flags 0x02 dlen 12 #22713 [hci0] 1664.426103 L2CAP: Connection Request (0x02) ident 18 len 4 PSM: 3 (0x0003) Source CID: 65 < ACL Data TX: Handle 43 flags 0x00 dlen 16 #22714 [hci0] 1664.426186 L2CAP: Connection Response (0x03) ident 18 len 8 Destination CID: 66 Source CID: 65 Result: Connection successful (0x0000) Status: No further information available (0x0000) < ACL Data TX: Handle 43 flags 0x00 dlen 27 #22715 [hci0] 1664.426196 L2CAP: Configure Request (0x04) ident 13 len 19 Destination CID: 65 Flags: 0x0000 Option: Maximum Transmission Unit (0x01) [mandatory] MTU: 1013 Option: Retransmission and Flow Control (0x04) [mandatory] Mode: Basic (0x00) TX window size: 0 Max transmit: 0 Retransmission timeout: 0 Monitor timeout: 0 Maximum PDU size: 0 > ACL Data RX: Handle 43 flags 0x02 dlen 16 #22716 [hci0] 1664.428804 L2CAP: Connection Response (0x03) ident 12 len 8 Destination CID: 66 Source CID: 65 Result: Connection successful (0x0000) Status: No further information available (0x0000) *snip* Fix is to check that channel is in state BT_DISCONN before deleting the channel. This bug was found while fuzzing Bluez's OBEX implementation using Synopsys Defensics. Reported-by: Matti Kamunen <matti.kamunen@synopsys.com> Reported-by: Ari Timonen <ari.timonen@synopsys.com> Signed-off-by: Matias Karhumaa <matias.karhumaa@gmail.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
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