CVE-2013-1774 (C, published 2013-02-28T19:55Z)
Description: value: The chase_port function in drivers/usb/serial/io_ti.c in the Linux kernel before 3.7.4 allows local users to cause a denial of service (NULL pointer dereference and system crash) via an attempted /dev/ttyUSB read or write operation on a disconnected Edgeport USB serial converter.
Severity: MEDIUM (CVSS v3 base score: )
Weakness: CWE-264 \u2014 Permissions, Privileges, and Access Controls
Weaknesses in this category are related to the management of permissions, privileges, and other security features that are used to perform access control.
Repository: https://github.com/torvalds/linux
Files changed:
drivers/usb/serial/io_ti.c
Commit message: USB: io_ti: Fix NULL dereference in chase_port()

The tty is NULL when the port is hanging up.
chase_port() needs to check for this.

This patch is intended for stable series.
The behavior was observed and tested in Linux 3.2 and 3.7.1.

Johan Hovold submitted a more elaborate patch for the mainline kernel.

[   56.277883] usb 1-1: edge_bulk_in_callback - nonzero read bulk status received: -84
[   56.278811] usb 1-1: USB disconnect, device number 3
[   56.278856] usb 1-1: edge_bulk_in_callback - stopping read!
[   56.279562] BUG: unable to handle kernel NULL pointer dereference at 00000000000001c8
[   56.280536] IP: [<ffffffff8144e62a>] _raw_spin_lock_irqsave+0x19/0x35
[   56.281212] PGD 1dc1b067 PUD 1e0f7067 PMD 0
[   56.282085] Oops: 0002 [#1] SMP
[   56.282744] Modules linked in:
[   56.283512] CPU 1
[   56.283512] Pid: 25, comm: khubd Not tainted 3.7.1 #1 innotek GmbH VirtualBox/VirtualBox
[   56.283512] RIP: 0010:[<ffffffff8144e62a>]  [<ffffffff8144e62a>] _raw_spin_lock_irqsave+0x19/0x35
[   56.283512] RSP: 0018:ffff88001fa99ab0  EFLAGS: 00010046
[   56.283512] RAX: 0000000000000046 RBX: 00000000000001c8 RCX: 0000000000640064
[   56.283512] RDX: 0000000000010000 RSI: ffff88001fa99b20 RDI: 00000000000001c8
[   56.283512] RBP: ffff88001fa99b20 R08: 0000000000000000 R09: 0000000000000000
[   56.283512] R10: 0000000000000000 R11: ffffffff812fcb4c R12: ffff88001ddf53c0
[   56.283512] R13: 0000000000000000 R14: 00000000000001c8 R15: ffff88001e19b9f4
[   56.283512] FS:  0000000000000000(0000) GS:ffff88001fd00000(0000) knlGS:0000000000000000
[   56.283512] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[   56.283512] CR2: 00000000000001c8 CR3: 000000001dc51000 CR4: 00000000000006e0
[   56.283512] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[   56.283512] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
[   56.283512] Process khubd (pid: 25, threadinfo ffff88001fa98000, task ffff88001fa94f80)
[   56.283512] Stack:
[   56.283512]  0000000000000046 00000000000001c8 ffffffff810578ec ffffffff812fcb4c
[   56.283512]  ffff88001e19b980 0000000000002710 ffffffff812ffe81 0000000000000001
[   56.283512]  ffff88001fa94f80 0000000000000202 ffffffff00000001 0000000000000296
[   56.283512] Call Trace:
[   56.283512]  [<ffffffff810578ec>] ? add_wait_queue+0x12/0x3c
[   56.283512]  [<ffffffff812fcb4c>] ? usb_serial_port_work+0x28/0x28
[   56.283512]  [<ffffffff812ffe81>] ? chase_port+0x84/0x2d6
[   56.283512]  [<ffffffff81063f27>] ? try_to_wake_up+0x199/0x199
[   56.283512]  [<ffffffff81263a5c>] ? tty_ldisc_hangup+0x222/0x298
[   56.283512]  [<ffffffff81300171>] ? edge_close+0x64/0x129
[   56.283512]  [<ffffffff810612f7>] ? __wake_up+0x35/0x46
[   56.283512]  [<ffffffff8106135b>] ? should_resched+0x5/0x23
[   56.283512]  [<ffffffff81264916>] ? tty_port_shutdown+0x39/0x44
[   56.283512]  [<ffffffff812fcb4c>] ? usb_serial_port_work+0x28/0x28
[   56.283512]  [<ffffffff8125d38c>] ? __tty_hangup+0x307/0x351
[   56.283512]  [<ffffffff812e6ddc>] ? usb_hcd_flush_endpoint+0xde/0xed
[   56.283512]  [<ffffffff8144e625>] ? _raw_spin_lock_irqsave+0x14/0x35
[   56.283512]  [<ffffffff812fd361>] ? usb_serial_disconnect+0x57/0xc2
[   56.283512]  [<ffffffff812ea99b>] ? usb_unbind_interface+0x5c/0x131
[   56.283512]  [<ffffffff8128d738>] ? __device_release_driver+0x7f/0xd5
[   56.283512]  [<ffffffff8128d9cd>] ? device_release_driver+0x1a/0x25
[   56.283512]  [<ffffffff8128d393>] ? bus_remove_device+0xd2/0xe7
[   56.283512]  [<ffffffff8128b7a3>] ? device_del+0x119/0x167
[   56.283512]  [<ffffffff812e8d9d>] ? usb_disable_device+0x6a/0x180
[   56.283512]  [<ffffffff812e2ae0>] ? usb_disconnect+0x81/0xe6
[   56.283512]  [<ffffffff812e4435>] ? hub_thread+0x577/0xe82
[   56.283512]  [<ffffffff8144daa7>] ? __schedule+0x490/0x4be
[   56.283512]  [<ffffffff8105798f>] ? abort_exclusive_wait+0x79/0x79
[   56.283512]  [<ffffffff812e3ebe>] ? usb_remote_wakeup+0x2f/0x2f
[   56.283512]  [<ffffffff812e3ebe>] ? usb_remote_wakeup+0x2f/0x2f
[   56.283512]  [<ffffffff810570b4>] ? kthread+0x81/0x89
[   56.283512]  [<ffffffff81057033>] ? __kthread_parkme+0x5c/0x5c
[   56.283512]  [<ffffffff8145387c>] ? ret_from_fork+0x7c/0xb0
[   56.283512]  [<ffffffff81057033>] ? __kthread_parkme+0x5c/0x5c
[   56.283512] Code: 8b 7c 24 08 e8 17 0b c3 ff 48 8b 04 24 48 83 c4 10 c3 53 48 89 fb 41 50 e8 e0 0a c3 ff 48 89 04 24 e8 e7 0a c3 ff ba 00 00 01 00
<f0> 0f c1 13 48 8b 04 24 89 d1 c1 ea 10 66 39 d1 74 07 f3 90 66
[   56.283512] RIP  [<ffffffff8144e62a>] _raw_spin_lock_irqsave+0x19/0x35
[   56.283512]  RSP <ffff88001fa99ab0>
[   56.283512] CR2: 00000000000001c8
[   56.283512] ---[ end trace 49714df27e1679ce ]---

Signed-off-by: Wolfgang Frisch <wfpub@roembden.net>
Cc: Johan Hovold <jhovold@gmail.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>


Vulnerable code:

Fixed code:
	if (!tty)
		return;