# CVE-2026-45904: powerpc/eeh: fix recursive pci_lock_rescan_remove locking in EEH event handling

Status: published. Published: 2026-05-27. Updated: 2026-11-06.

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---

## Remediation

No remediation reported in collected sources

## Affected products and versions

- Linux / Linux: ≥ 502f08831a9afb72dc98a56ae6504da43e93b250; < 89810e2d80281d42f855fac813786758ee16e323 (affected, git); ≥ f56e004b781719d8fdf6c9619b15caf2579bc1f2; < 788dd28fd49610d6047cbb15dbf1186afffdfbaf (affected, git); ≥ 59c6d3d81d42bf543c90597b4f38c53d6874c5a1; < f49faa4a64f8ac0e38983e606075b25dfcfc9ad4 (affected, git); ≥ a426e8a6ae161f51888585b065db0f8f93ab2e16; < 87a1f93986aa1500b85aeff16b0b71c29ea116ea (affected, git); ≥ d2c60a8a387e9fcc28447ef36c03f8e49fd052a6; < f8b16d5764ee1e78c1ef333017ad383ffe76fcdc (affected, git); ≥ 1010b4c012b0d78dfb9d3132b49aa2ef024a07a7; < 6e6561231c6cfc32c5631aeecc0928ff2b14265c (affected, git); ≥ 1010b4c012b0d78dfb9d3132b49aa2ef024a07a7; < b85ee287bfe52c6b2d9b41758b5e0d08679d5b39 (affected, git); ≥ 1010b4c012b0d78dfb9d3132b49aa2ef024a07a7; < 815a8d2feb5615ae7f0b5befd206af0b0160614c (affected, git); d42bbd8f30ac38b1ce54715bf08ec3dac18d6b25 (affected, git); 19d5036e7ad766cf212aebec23b9f1d7924a62bc (affected, git); ≥ 5.10.241; < 5.10.252 (affected, semver); ≥ 5.15.190; < 5.15.202 (affected, semver); ≥ 6.1.148; < 6.1.165 (affected, semver); ≥ 6.6.102; < 6.6.128 (affected, semver); ≥ 6.12.42; < 6.12.75 (affected, semver); ≥ 6.15.10; < 6.16 (affected, semver); ≥ 6.16.1; < 6.17 (affected, semver). Source: CNA: Linux
- Linux / Linux: 6.17 (affected); ≥ 0; < 6.17 (unaffected, semver); ≥ 5.10.252; ≤ 5.10.* (unaffected, semver); ≥ 5.15.202; ≤ 5.15.* (unaffected, semver); ≥ 6.1.165; ≤ 6.1.* (unaffected, semver); ≥ 6.6.128; ≤ 6.6.* (unaffected, semver); ≥ 6.12.75; ≤ 6.12.* (unaffected, semver); ≥ 6.18.14; ≤ 6.18.* (unaffected, semver); ≥ 6.19.4; ≤ 6.19.* (unaffected, semver); ≥ 7.0; ≤ * (unaffected, original_commit_for_fix). Source: CNA: Linux

## Severity and prioritization

- CISA KEV: No listing in collected sources

- EPSS: 0.16% as of 2026-11-06; percentile 5.27%

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: Not reported

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://git.kernel.org/stable/c/89810e2d80281d42f855fac813786758ee16e323 (CNA: Linux)

- https://git.kernel.org/stable/c/788dd28fd49610d6047cbb15dbf1186afffdfbaf (CNA: Linux)

- https://git.kernel.org/stable/c/f49faa4a64f8ac0e38983e606075b25dfcfc9ad4 (CNA: Linux)

- https://git.kernel.org/stable/c/87a1f93986aa1500b85aeff16b0b71c29ea116ea (CNA: Linux)

- https://git.kernel.org/stable/c/f8b16d5764ee1e78c1ef333017ad383ffe76fcdc (CNA: Linux)

- https://git.kernel.org/stable/c/6e6561231c6cfc32c5631aeecc0928ff2b14265c (CNA: Linux)

- https://git.kernel.org/stable/c/b85ee287bfe52c6b2d9b41758b5e0d08679d5b39 (CNA: Linux)

- https://git.kernel.org/stable/c/815a8d2feb5615ae7f0b5befd206af0b0160614c (CNA: Linux)

## Provenance

- CNA: Linux: https://www.cve.org/CVERecord?id=CVE-2026-45904; retrieved 2026-11-06; source updated 2026-11-06

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-45904; retrieved 2026-11-06; source updated Not reported

Revision: 747ad9f55a2946a2bb436b6afda72910f7c08d6dc1a02c0c62c7c1580d06d259

Canonical: https://y2.dev/cve/CVE-2026-45904

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