CVE-2026-81005

ipmi: si: Fix NULL pointer dereference after failed registration

Published Sep 11, 2026 CVSS 3.1 · 4.1 Medium EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Debian DLA Debian DLA DLA-4817-1 linux-6.12 security update
Debian DLA Debian DLA DLA-4841-1 linux security update
Debian DSA Debian DSA DSA-6528-1 linux security update
Ubuntu USN Ubuntu USN USN-8961-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-9019-1 Linux kernel (Azure) vulnerabilities
Ubuntu USN Ubuntu USN USN-9020-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-9022-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-9023-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-9024-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-9025-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-9026-1 Linux kernel (Azure) vulnerabilities
Ubuntu USN Ubuntu USN USN-9029-1 Linux kernel (Raspberry Pi) vulnerabilities
Ubuntu USN Ubuntu USN USN-9039-1 Linux kernel (Azure CVM) vulnerabilities
Ubuntu USN Ubuntu USN USN-9040-1 Linux kernel (Low Latency NVIDIA) vulnerabilities
Ubuntu USN Ubuntu USN USN-9066-1 Linux kernel (HWE) vulnerabilities
Ubuntu USN Ubuntu USN USN-9091-1 Linux kernel (NVIDIA Tegra) vulnerabilities
History
Type Values Removed Values Added
References
Metrics threat_severity

None

cvssV3_1

{'score': 4.1, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H'}

threat_severity

Moderate

Type Values Removed Values Added
Weaknesses CWE-476
Type Values Removed Values Added
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.
Title ipmi: si: Fix NULL pointer dereference after failed registration
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References
Weaknesses

Sources

Status
PUBLISHED
Assigner
Linux
Published
Updated
Oct 19, 2026, 8:46 AM
Reserved
Aug 26, 2026, 2:34 PM
Status
Received
Published
Sep 11, 2026, 8:19 PM
Modified
Oct 19, 2026, 9:17 AM
Severity
Moderate
Public date
Sep 11, 2026, 12:00 AM