CVE-2024-41036

In the Linux kernel, the following vulnerability has been resolved:

net: ks8851: Fix deadlock with the SPI chip variant

When SMP is enabled and spinlocks are actually functional then there is a deadlock with the statelock spinlock between ks8851_start_xmit_spi and ks8851_irq:

watchdog: BUG: soft lockup - CPU#0 stuck for 27s!
call trace:
  queued_spin_lock_slowpath+0x100/0x284
  do_raw_spin_lock+0x34/0x44
  ks8851_start_xmit_spi+0x30/0xb8
  ks8851_start_xmit+0x14/0x20
  netdev_start_xmit+0x40/0x6c
  dev_hard_start_xmit+0x6c/0xbc
  sch_direct_xmit+0xa4/0x22c
  __qdisc_run+0x138/0x3fc
  qdisc_run+0x24/0x3c
  net_tx_action+0xf8/0x130
  handle_softirqs+0x1ac/0x1f0
  __do_softirq+0x14/0x20
  ____do_softirq+0x10/0x1c
  call_on_irq_stack+0x3c/0x58
  do_softirq_own_stack+0x1c/0x28
  __irq_exit_rcu+0x54/0x9c
  irq_exit_rcu+0x10/0x1c
  el1_interrupt+0x38/0x50
  el1h_64_irq_handler+0x18/0x24
  el1h_64_irq+0x64/0x68
  __netif_schedule+0x6c/0x80
  netif_tx_wake_queue+0x38/0x48
  ks8851_irq+0xb8/0x2c8
  irq_thread_fn+0x2c/0x74
  irq_thread+0x10c/0x1b0
  kthread+0xc8/0xd8
  ret_from_fork+0x10/0x20

This issue has not been identified earlier because tests were done on a device with SMP disabled and so spinlocks were actually NOPs.

Now use spin_(un)lock_bh for TX queue related locking to avoid execution of softirq work synchronously that would lead to a deadlock.

Weakness

The product does not properly acquire or release a lock on a resource, leading to unexpected resource state changes and behaviors.

Affected Software

Extended Description

Locking is a type of synchronization behavior that ensures that multiple independently-operating processes or threads do not interfere with each other when accessing the same resource. All processes/threads are expected to follow the same steps for locking. If these steps are not followed precisely - or if no locking is done at all - then another process/thread could modify the shared resource in a way that is not visible or predictable to the original process. This can lead to data or memory corruption, denial of service, etc.

Potential Mitigations

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/25.html
• https://cwe.mitre.org/data/definitions/26.html
• https://cwe.mitre.org/data/definitions/27.html

References

• https://git.kernel.org/stable/c/0913ec336a6c0c4a2b296bd9f74f8e41c4c83c8c
• https://git.kernel.org/stable/c/10fec0cd0e8f56ff06c46bb24254c7d8f8f2bbf0
• https://git.kernel.org/stable/c/80ece00137300d74642f2038c8fe5440deaf9f05
• https://git.kernel.org/stable/c/a0c69c492f4a8fad52f0a97565241c926160c9a4
• https://git.kernel.org/stable/c/0913ec336a6c0c4a2b296bd9f74f8e41c4c83c8c
• https://git.kernel.org/stable/c/10fec0cd0e8f56ff06c46bb24254c7d8f8f2bbf0
• https://git.kernel.org/stable/c/80ece00137300d74642f2038c8fe5440deaf9f05
• https://git.kernel.org/stable/c/a0c69c492f4a8fad52f0a97565241c926160c9a4