CVE-2022-49201

There is a race between reset and the transmit paths that can lead to ibmvnic_xmit() accessing an scrq after it has been freed in the reset path. It can result in a crash like:

Kernel attempted to read user page (0) - exploit attempt? (uid: 0)
BUG: Kernel NULL pointer dereference on read at 0x00000000
Faulting instruction address: 0xc0080000016189f8
Oops: Kernel access of bad area, sig: 11 [#1]
...
NIP [c0080000016189f8] ibmvnic_xmit+0x60/0xb60 [ibmvnic]
LR [c000000000c0046c] dev_hard_start_xmit+0x11c/0x280
Call Trace:
[c008000001618f08] ibmvnic_xmit+0x570/0xb60 [ibmvnic] (unreliable)
[c000000000c0046c] dev_hard_start_xmit+0x11c/0x280
[c000000000c9cfcc] sch_direct_xmit+0xec/0x330
[c000000000bfe640] __dev_xmit_skb+0x3a0/0x9d0
[c000000000c00ad4] __dev_queue_xmit+0x394/0x730
[c008000002db813c] __bond_start_xmit+0x254/0x450 [bonding]
[c008000002db8378] bond_start_xmit+0x40/0xc0 [bonding]
[c000000000c0046c] dev_hard_start_xmit+0x11c/0x280
[c000000000c00ca4] __dev_queue_xmit+0x564/0x730
[c000000000cf97e0] neigh_hh_output+0xd0/0x180
[c000000000cfa69c] ip_finish_output2+0x31c/0x5c0
[c000000000cfd244] __ip_queue_xmit+0x194/0x4f0
[c000000000d2a3c4] __tcp_transmit_skb+0x434/0x9b0
[c000000000d2d1e0] __tcp_retransmit_skb+0x1d0/0x6a0
[c000000000d2d984] tcp_retransmit_skb+0x34/0x130
[c000000000d310e8] tcp_retransmit_timer+0x388/0x6d0
[c000000000d315ec] tcp_write_timer_handler+0x1bc/0x330
[c000000000d317bc] tcp_write_timer+0x5c/0x200
[c000000000243270] call_timer_fn+0x50/0x1c0
[c000000000243704] __run_timers.part.0+0x324/0x460
[c000000000243894] run_timer_softirq+0x54/0xa0
[c000000000ea713c] __do_softirq+0x15c/0x3e0
[c000000000166258] __irq_exit_rcu+0x158/0x190
[c000000000166420] irq_exit+0x20/0x40
[c00000000002853c] timer_interrupt+0x14c/0x2b0
[c000000000009a00] decrementer_common_virt+0x210/0x220
--- interrupt: 900 at plpar_hcall_norets_notrace+0x18/0x2c

The immediate cause of the crash is the access of txscrq in the following snippet during a reset, where the txscrq can be either NULL or an address that will soon be invalid:

ibmvnic_xmit()
{
    ...
    tx_scrq = adapter->tx_scrq[queue_num];
    txq = netdev_get_tx_queue(netdev, queue_num);
    ind_bufp = &tx_scrq->ind_buf;

    if (test_bit(0, &adapter->resetting)) {
    ...
}

But beyond that, the call to ibmvnicxmit() itself is not safe during a reset and the reset path attempts to avoid this by stopping the queue in ibmvniccleanup(). However just after the queue was stopped, an in-flight ibmvniccompletetx() could have restarted the queue even as the reset is progressing.

Since the queue was restarted we could get a call to ibmvnicxmit() which can then access the bad txscrq (or other fields).

We cannot however simply have ibmvniccompletetx() check the ->resetting bit and skip starting the queue. This can race at the "back-end" of a good reset which just restarted the queue but has not cleared the ->resetting bit yet. If we skip restarting the queue due to ->resetting being true, the queue would remain stopped indefinitely potentially leading to transmit timeouts.

IOW ->resetting is too broad for this purpose. Instead use a new flag that indicates whether or not the queues are active. Only the open/ reset paths control when the queues are active. ibmvniccompletetx() and others wake up the queue only if the queue is marked active.

So we will have: A. reset/open thread in ibmvniccleanup() and _ibmvnic_open()

    ->resetting = true
    ->tx_queues_active = false
    disable tx queues
    ...
    ->tx_queues_active = true
    start tx queues

B. Tx interrupt in ibmvnic_complete_tx():

    if (->tx_queues_active)
        netif_wake_subqueue();

To ensure that ->txqueuesactive and state of the queues are consistent, we need a lock which:

- must also be taken in the interrupt path (ibmvnic_complete_tx())
- shared across the multiple

---truncated---

References

Affected packages

Debian:11 / linux

Package

Name: linux
Purl: pkg:deb/debian/linux?arch=source

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0Unknown introduced version / All previous versions are affected

Affected versions

5.*

5.10.46-4

5.10.46-5

5.10.70-1~bpo10+1

5.10.70-1

5.10.84-1

5.10.92-1~bpo10+1

5.10.92-1

5.10.92-2

5.10.103-1~bpo10+1

5.10.103-1

5.10.106-1

5.10.113-1

5.10.120-1~bpo10+1

5.10.120-1

5.10.127-1

5.10.127-2~bpo10+1

5.10.127-2

5.10.136-1

5.10.140-1

5.10.148-1

5.10.149-1

5.10.149-2

5.10.158-1

5.10.158-2

5.10.162-1

5.10.178-1

5.10.178-2

5.10.178-3

5.10.179-1

5.10.179-2

5.10.179-3

5.10.179-4

5.10.179-5

5.10.191-1

5.10.197-1

5.10.205-1

5.10.205-2

5.10.209-1

5.10.209-2

5.10.216-1

5.10.218-1

5.10.221-1

5.10.223-1

5.10.226-1

5.10.234-1

5.13.9-1~exp1

5.13.9-1~exp2

5.13.12-1~exp1

5.14-1~exp1

5.14-1~exp2

5.14.1-1~exp1

5.14.2-1~exp1

5.14.3-1~exp1

5.14.6-1

5.14.6-2

5.14.6-3

5.14.9-1

5.14.9-2~bpo11+1

5.14.9-2

5.14.12-1

5.14.16-1

5.15-1~exp1

5.15.1-1~exp1

5.15.2-1~exp1

5.15.3-1

5.15.5-1

5.15.5-2~bpo11+1

5.15.5-2

5.15.15-1

5.15.15-2~bpo11+1

5.15.15-2

5.16~rc1-1~exp1

5.16~rc3-1~exp1

5.16~rc4-1~exp1

5.16~rc5-1~exp1

5.16~rc6-1~exp1

5.16~rc7-1~exp1

5.16~rc8-1~exp1

5.16.3-1~exp1

5.16.4-1~exp1

5.16.7-1

5.16.7-2

5.16.10-1

5.16.11-1~bpo11+1

5.16.11-1

5.16.12-1~bpo11+1

5.16.12-1

5.16.14-1

5.16.18-1

5.17~rc3-1~exp1

5.17~rc4-1~exp1

5.17~rc5-1~exp1

5.17~rc6-1~exp1

5.17~rc7-1~exp1

5.17~rc8-1~exp1

5.17.1-1~exp1

5.17.3-1

5.17.6-1

5.17.11-1

5.18-1~exp1

5.18.2-1~bpo11+1

5.18.2-1

5.18.5-1

5.18.14-1~bpo11+1

5.18.14-1

5.18.16-1~bpo11+1

5.18.16-1

5.19~rc4-1~exp1

5.19~rc6-1~exp1

5.19-1~exp1

5.19.6-1

5.19.11-1~bpo11+1

5.19.11-1

6.*

6.0~rc7-1~exp1

6.0-1~exp1

6.0.2-1

6.0.3-1~bpo11+1

6.0.3-1

6.0.5-1

6.0.6-1

6.0.6-2

6.0.7-1

6.0.8-1

6.0.10-1

6.0.10-2

6.0.12-1~bpo11+1

6.0.12-1

6.0.12-1+alpha

6.1~rc3-1~exp1

6.1~rc5-1~exp1

6.1~rc6-1~exp1

6.1~rc7-1~exp1

6.1~rc8-1~exp1

6.1.1-1~exp1

6.1.1-1~exp2

6.1.2-1~exp1

6.1.4-1

6.1.7-1

6.1.8-1

6.1.8-1+sh4

6.1.11-1

6.1.12-1~bpo11+1

6.1.12-1

6.1.15-1~bpo11+1

6.1.15-1

6.1.20-1~bpo11+1

6.1.20-1

6.1.20-2~bpo11+1

6.1.20-2

6.1.25-1

6.1.27-1~bpo11+1

6.1.27-1

6.1.37-1

6.1.38-1

6.1.38-2~bpo11+1

6.1.38-2

6.1.38-3

6.1.38-4~bpo11+1

6.1.38-4

6.1.52-1

6.1.55-1~bpo11+1

6.1.55-1

6.1.64-1

6.1.66-1

6.1.67-1

6.1.69-1~bpo11+1

6.1.69-1

6.1.76-1~bpo11+1

6.1.76-1

6.1.82-1

6.1.85-1

6.1.90-1~bpo11+1

6.1.90-1

6.1.94-1~bpo11+1

6.1.94-1

6.1.98-1

6.1.99-1

6.1.106-1

6.1.106-2

6.1.106-3

6.1.112-1

6.1.115-1

6.1.119-1

6.1.123-1

6.1.124-1

6.1.128-1

6.1.129-1

6.3.1-1~exp1

6.3.2-1~exp1

6.3.4-1~exp1

6.3.5-1~exp1

6.3.7-1~bpo12+1

6.3.7-1

6.3.11-1

6.4~rc6-1~exp1

6.4~rc7-1~exp1

6.4.1-1~exp1

6.4.4-1~bpo12+1

6.4.4-1

6.4.4-2

6.4.4-3~bpo12+1

6.4.4-3

6.4.11-1

6.4.13-1

6.5~rc4-1~exp1

6.5~rc6-1~exp1

6.5~rc7-1~exp1

6.5.1-1~exp1

6.5.3-1~bpo12+1

6.5.3-1

6.5.6-1

6.5.8-1

6.5.10-1~bpo12+1

6.5.10-1

6.5.13-1

6.6.3-1~exp1

6.6.4-1~exp1

6.6.7-1~exp1

6.6.8-1

6.6.9-1

6.6.11-1

6.6.13-1~bpo12+1

6.6.13-1

6.6.15-1

6.6.15-2

6.7-1~exp1

6.7.1-1~exp1

6.7.4-1~exp1

6.7.7-1

6.7.9-1

6.7.9-2

6.7.12-1~bpo12+1

6.7.12-1

6.8.9-1

6.8.11-1

6.8.12-1~bpo12+1

6.8.12-1

6.9.2-1~exp1

6.9.7-1~bpo12+1

6.9.7-1

6.9.8-1

6.9.9-1

6.9.10-1~bpo12+1

6.9.10-1

6.9.11-1

6.9.12-1

6.10-1~exp1

6.10.1-1~exp1

6.10.3-1

6.10.4-1

6.10.6-1~bpo12+1

6.10.6-1

6.10.7-1

6.10.9-1

6.10.11-1~bpo12+1

6.10.11-1

6.10.12-1

6.11~rc4-1~exp1

6.11~rc5-1~exp1

6.11-1~exp1

6.11.2-1

6.11.4-1

6.11.5-1~bpo12+1

6.11.5-1

6.11.6-1

6.11.7-1

6.11.9-1

6.11.10-1~bpo12+1

6.11.10-1

6.12~rc6-1~exp1

6.12.3-1

6.12.5-1

6.12.6-1

6.12.8-1

6.12.9-1~bpo12+1

6.12.9-1

6.12.9-1+alpha

6.12.10-1

6.12.11-1

6.12.11-1+alpha

6.12.11-1+alpha.1

6.12.12-1~bpo12+1

6.12.12-1

6.12.13-1

6.12.15-1

6.12.16-1

6.12.17-1

6.12.19-1

6.13~rc6-1~exp1

6.13~rc7-1~exp1

6.13.2-1~exp1

6.13.3-1~exp1

6.13.4-1~exp1

6.13.5-1~exp1

6.13.6-1~exp1

6.13.7-1~exp1

Ecosystem specific

{
    "urgency": "not yet assigned"
}

Debian:12 / linux

Package

Name: linux
Purl: pkg:deb/debian/linux?arch=source

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0Unknown introduced version / All previous versions are affected

Fixed

5.17.3-1

Ecosystem specific

{
    "urgency": "not yet assigned"
}

Debian:13 / linux

Package

Name: linux
Purl: pkg:deb/debian/linux?arch=source

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0Unknown introduced version / All previous versions are affected

Fixed

5.17.3-1

Ecosystem specific

{
    "urgency": "not yet assigned"
}