CVE-2023-53094: tty: serial: fsl_lpuart: fix race on RX DMA shutdown

Severity: medium (CVSS 4.7 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-05-02 · updated 2026-08-04
Weakness: CWE-362

Description

In the Linux kernel, the following vulnerability has been resolved: tty: serial: fsl_lpuart: fix race on RX DMA shutdown From time to time DMA completion can come in the middle of DMA shutdown: <process ctx>: <IRQ>: lpuart32_shutdown() lpuart_dma_shutdown() del_timer_sync() lpuart_dma_rx_complete() lpuart_copy_rx_to_tty() mod_timer() lpuart_dma_rx_free() When the timer fires a bit later, sport->dma_rx_desc is NULL: Unable to handle kernel NULL pointer dereference at virtual address 0000000000000004 pc : lpuart_copy_rx_to_tty+0xcc/0x5bc lr : lpuart_timer_func+0x1c/0x2c Call trace: lpuart_copy_rx_to_tty lpuart_timer_func call_timer_fn __run_timers.part.0 run_timer_softirq __do_softirq __irq_exit_rcu irq_exit handle_domain_irq gic_handle_irq call_on_irq_stack do_interrupt_handler ... To fix this fold del_timer_sync() into lpuart_dma_rx_free() after dmaengine_terminate_sync() to make sure timer will not be re-started in lpuart_copy_rx_to_tty() <= lpuart_dma_rx_complete().

Affected products

Linux kernel: from 3.18.9 before 3.19; from 3.19.1 before 5.10.177; from 5.11 before 5.15.105; from 5.16 before 6.1.23; from 6.2 before 6.2.8; 6.3-rc1, 6.3-rc2 — fixed in 3.19, 5.10.177, 5.15.105, 6.1.23, 6.2.8

How to fix

Upgrade to a fixed version: Linux kernel 3.19, 5.10.177, 5.15.105, 6.1.23. Check the vendor advisory for mitigations.

References

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