CVE-2022-49613
serial: 8250: Fix PM usage_count for console handover
In the Linux kernel, the following vulnerability has been resolved: serial: 8250: Fix PM usage_count for console handover When console is enabled, univ8250_console_setup() calls serial8250_console_setup() before .dev is set to uart_port. Therefore, it will not call pm_runtime_get_sync(). Later, when the actual driver is going to take over univ8250_console_exit() is called. As .dev is already set, serial8250_console_exit() makes pm_runtime_put_sync() call with usage count being zero triggering PM usage count warning (extra debug for univ8250_console_setup(), univ8250_console_exit(), and serial8250_register_ports()): [ 0.068987] univ8250_console_setup ttyS0 nodev [ 0.499670] printk: console [ttyS0] enabled [ 0.717955] printk: console [ttyS0] printing thread started [ 1.960163] serial8250_register_ports assigned dev for ttyS0 [ 1.976830] printk: console [ttyS0] disabled [ 1.976888] printk: console [ttyS0] printing thread stopped [ 1.977073] univ8250_console_exit ttyS0 usage:0 [ 1.977075] serial8250 serial8250: Runtime PM usage count underflow! [ 1.977429] dw-apb-uart.6: ttyS0 at MMIO 0x4010006000 (irq = 33, base_baud = 115200) is a 16550A [ 1.977812] univ8250_console_setup ttyS0 usage:2 [ 1.978167] printk: console [ttyS0] printing thread started [ 1.978203] printk: console [ttyS0] enabled To fix the issue, call pm_runtime_get_sync() in serial8250_register_ports() as soon as .dev is set for an uart_port if it has console enabled. This problem became apparent only recently because 82586a721595 ("PM: runtime: Avoid device usage count underflows") added the warning printout. I confirmed this problem also occurs with v5.18 (w/o the warning printout, obviously).
Fixes and workarounds
No remediation reported in collected sources.
Missing remediation information is not evidence that no patch exists.
Affected products and versions
| Product | Versions | Authority |
|---|---|---|
| Linux Linux |
≥ bedb404e91bb2908d9921fc736a518a9d89525fc; < d9cb6fabc90102f9e61fe35bd0160db88f4f53b4 (affected, git) ≥ bedb404e91bb2908d9921fc736a518a9d89525fc; < 190ce5cdc55d1b66ea582ac2be6fd5a72e3cc486 (affected, git) ≥ bedb404e91bb2908d9921fc736a518a9d89525fc; < 5df66302f03f87ae8953785a882d78e911f00c55 (affected, git) ≥ bedb404e91bb2908d9921fc736a518a9d89525fc; < f9b11229b79c0fb2100b5bb4628a101b1d37fbf6 (affected, git) Other versions: unaffected |
CNA: Linux |
| Linux Linux |
5.7 (affected) ≥ 0; < 5.7 (unaffected, semver) ≥ 5.10.132; ≤ 5.10.* (unaffected, semver) ≥ 5.15.56; ≤ 5.15.* (unaffected, semver) ≥ 5.18.13; ≤ 5.18.* (unaffected, semver) ≥ 5.19; ≤ * (unaffected, original_commit_for_fix) Other versions: affected |
CNA: Linux |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
No CVSS assessment reported. An unscored record is not a low-severity determination.
Exploit evidence
No exploit evidence in collected sources. This is not proof of no exploitation.
References
- https://git.kernel.org/stable/c/d9cb6fabc90102f9e61fe35bd0160db88f4f53b4CNA: Linux
- https://git.kernel.org/stable/c/190ce5cdc55d1b66ea582ac2be6fd5a72e3cc486CNA: Linux
- https://git.kernel.org/stable/c/5df66302f03f87ae8953785a882d78e911f00c55CNA: Linux
- https://git.kernel.org/stable/c/f9b11229b79c0fb2100b5bb4628a101b1d37fbf6CNA: Linux
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