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Linux Kernel CVE-2026-45904

| EUVDEUVD-2026-32370 MEDIUM
Uncontrolled Recursion (CWE-674)
2026-05-27 416baaa9-dc9f-4396-8d5f-8c081fb06d67 GHSA-5f94-f58j-vgqv
Linux IBM Information Disclosure Red Hat Suse
5.5
CVSS 3.1 · NVD
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Severity by source

NVD PRIMARY
5.5 MEDIUM
AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
vuln.today AI
5.5 MEDIUM

Local access with low privileges needed to be present when EEH events fire; deadlock impacts only availability with zero data exposure.

3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
4.0 AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
SUSE
MEDIUM
qualitative
Red Hat
5.5 LOW
qualitative

Primary rating from NVD.

CVSS VectorNVD

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Lifecycle Timeline

5
Analysis Generated
Jun 24, 2026 - 16:39 vuln.today
CVSS changed
Jun 24, 2026 - 16:37 NVD
5.5 (MEDIUM)
Patch available
May 27, 2026 - 19:46 EUVD
CVE Published
May 27, 2026 - 14:17 nvd
MEDIUM 5.5
CVE Published
May 27, 2026 - 14:17 nvd
UNKNOWN (no severity yet)

DescriptionNVD

In the Linux kernel, the following vulnerability has been resolved:

powerpc/eeh: fix recursive pci_lock_rescan_remove locking in EEH event handling

The recent commit 1010b4c012b0 ("powerpc/eeh: Make EEH driver device hotplug safe") restructured the EEH driver to improve synchronization with the PCI hotplug layer.

However, it inadvertently moved pci_lock_rescan_remove() outside its intended scope in eeh_handle_normal_event(), leading to broken PCI error reporting and improper EEH event triggering. Specifically, eeh_handle_normal_event() acquired pci_lock_rescan_remove() before calling eeh_pe_bus_get(), but eeh_pe_bus_get() itself attempts to acquire the same lock internally, causing nested locking and disrupting normal EEH event handling paths.

This patch adds a boolean parameter do_lock to _eeh_pe_bus_get(), with two public wrappers: eeh_pe_bus_get() with locking enabled. eeh_pe_bus_get_nolock() that skips locking.

Callers that already hold pci_lock_rescan_remove() now use eeh_pe_bus_get_nolock() to avoid recursive lock acquisition.

Additionally, pci_lock_rescan_remove() calls are restored to the correct position-after eeh_pe_bus_get() and immediately before iterating affected PEs and devices. This ensures EEH-triggered PCI removes occur under proper bus rescan locking without recursive lock contention.

The eeh_pe_loc_get() function has been split into two functions: eeh_pe_loc_get(struct eeh_pe *pe) which retrieves the loc for given PE. eeh_pe_loc_get_bus(struct pci_bus *bus) which retrieves the location code for given bus.

This resolves lockdep warnings such as: <snip> [ 84.964298] [ T928] ============ [ 84.964304] [ T928] WARNING: possible recursive locking detected [ 84.964311] [ T928] 6.18.0-rc3 #51 Not tainted [ 84.964315] [ T928] -------------------------------------------- [ 84.964320] [ T928] eehd/928 is trying to acquire lock: [ 84.964324] [ T928] c000000003b29d58 (pci_rescan_remove_lock){+.+.}-{3:3}, at: pci_lock_rescan_remove+0x28/0x40 [ 84.964342] [ T928] but task is already holding lock: [ 84.964347] [ T928] c000000003b29d58 (pci_rescan_remove_lock){+.+.}-{3:3}, at: pci_lock_rescan_remove+0x28/0x40 [ 84.964357] [ T928] other info that might help us debug this: [ 84.964363] [ T928] Possible unsafe locking scenario:

[ 84.964367] [ T928] CPU0 [ 84.964370] [ T928] ---- [ 84.964373] [ T928] lock(pci_rescan_remove_lock); [ 84.964378] [ T928] lock(pci_rescan_remove_lock); [ 84.964383] [ T928] * DEADLOCK *

[ 84.964388] [ T928] May be due to missing lock nesting notation

[ 84.964393] [ T928] 1 lock held by eehd/928: [ 84.964397] [ T928] #0: c000000003b29d58 (pci_rescan_remove_lock){+.+.}-{3:3}, at: pci_lock_rescan_remove+0x28/0x40 [ 84.964408] [ T928] stack backtrace: [ 84.964414] [ T928] CPU: 2 UID: 0 PID: 928 Comm: eehd Not tainted 6.18.0-rc3 #51 VOLUNTARY [ 84.964417] [ T928] Hardware name: IBM,9080-HEX POWER10 (architected) 0x800200 0xf000006 of:IBM,FW1060.00 (NH1060_022) hv:phyp pSeries [ 84.964419] [ T928] Call Trace: [ 84.964420] [ T928] [c0000011a7157990] [c000000001705de4] dump_stack_lvl+0xc8/0x130 (unreliable) [ 84.964424] [ T928] [c0000011a71579d0] [c0000000002f66e0] print_deadlock_bug+0x430/0x440 [ 84.964428] [ T928] [c0000011a7157a70] [c0000000002fd0c0] __lock_acquire+0x1530/0x2d80 [ 84.964431] [ T928] [c0000011a7157ba0] [c0000000002fea54] lock_acquire+0x144/0x410 [ 84.964433] [ T928] [c0000011a7157cb0] [c0000011a7157cb0] __mutex_lock+0xf4/0x1050 [ 84.964436] [ T928] [c0000011a7157e00] [c000000000de21d8] pci_lock_rescan_remove+0x28/0x40 [ 84.964439] [ T928] [c0000011a7157e20] [c00000000004ed98] eeh_pe_bus_get+0x48/0xc0 [ 84.964442] [ T928] [c0000011a7157e50] [c00000 ---truncated---

AnalysisAI

Recursive mutex deadlock in the Linux kernel's PowerPC Enhanced Error Handling (EEH) subsystem causes denial of service on IBM POWER systems running affected kernel versions. Commit 1010b4c012b0 inadvertently repositioned pci_lock_rescan_remove() calls so that eeh_handle_normal_event() holds the lock before invoking eeh_pe_bus_get(), which internally attempts to acquire the same mutex, producing a confirmed lockdep-detected deadlock that crashes the EEH daemon and disables PCI error recovery. No public exploit has been identified and the EPSS score of 0.02% (7th percentile) reflects the narrow hardware-specific attack surface; real-world impact is a reliability and availability concern for IBM POWER server operators rather than a traditional security attack vector.

Technical ContextAI

The EEH (Enhanced Error Handling) subsystem in the Linux kernel provides hardware-assisted PCI bus error detection and recovery on IBM PowerPC and POWER platforms. The affected synchronization primitive is pci_rescan_remove_lock, a mutex shared between PCI hotplug and EEH event processing paths. A prior refactor (commit 1010b4c012b0, 'Make EEH driver device hotplug safe') moved the pci_lock_rescan_remove() acquisition to a scope encompassing the eeh_pe_bus_get() call, which itself calls pci_lock_rescan_remove() internally - producing a non-reentrant recursive mutex acquisition. CWE-674 (Incorrect Control Flow Scoping) captures this pattern precisely: a synchronization primitive is placed in the wrong lexical scope, creating a call-graph-level double-acquisition. The fix introduces eeh_pe_bus_get_nolock() for call sites that already hold the lock and restores the lock acquisition to immediately before PE/device iteration. Affected CPE is cpe:2.3:o:linux:linux_kernel:* across eight stable branches as confirmed by kernel.org stable commit references.

RemediationAI

Upgrade the Linux kernel to a patched stable release: 5.10.252, 5.15.202, 6.1.165, 6.6.128, 6.12.75, 6.18.14, or 6.19.4, each containing the relevant backport commits available at https://git.kernel.org/stable/c/6e6561231c6cfc32c5631aeecc0928ff2b14265c and the seven companion stable commits listed in the references. Distribution maintainers targeting IBM POWER (Red Hat, SUSE, Canonical, IBM's own kernel packages) should be monitored for corresponding package updates. As a temporary compensating control on non-critical systems only, adding eeh=off to the kernel boot parameters via GRUB will prevent the EEH daemon from processing events and avoid the deadlock; however, this entirely disables PCI hardware error recovery, eliminating fault tolerance on IBM POWER hardware and is strongly discouraged for production systems where reliability is required. No workaround preserves EEH functionality while mitigating the deadlock prior to patching.

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Vendor StatusVendor

SUSE

Severity: Moderate
Product Status
SUSE Linux Enterprise Desktop 15 SP7 Not-Affected
SUSE Linux Enterprise Desktop 15 SP7 Not-Affected
SUSE Linux Enterprise High Availability Extension 15 SP7 Not-Affected
SUSE Linux Enterprise High Availability Extension 15 SP7 Not-Affected
SUSE Linux Enterprise High Performance Computing 15 SP7 Not-Affected

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CVE-2026-45904 vulnerability details – vuln.today
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