CVE-2022-50045

powerpc/pci: Fix get_phb_number() locking

Published Jun 18, 2025 CVSS 3.1 · 5.5 Medium EPSS < 1% KEV · Not listed
Description
In the Linux kernel, the following vulnerability has been resolved:

powerpc/pci: Fix get_phb_number() locking

The recent change to get_phb_number() causes a DEBUG_ATOMIC_SLEEP
warning on some systems:

BUG: sleeping function called from invalid context at kernel/locking/mutex.c:580
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 1, name: swapper
preempt_count: 1, expected: 0
RCU nest depth: 0, expected: 0
1 lock held by swapper/1:
#0: c157efb0 (hose_spinlock){+.+.}-{2:2}, at: pcibios_alloc_controller+0x64/0x220
Preemption disabled at:
[<00000000>] 0x0
CPU: 0 PID: 1 Comm: swapper Not tainted 5.19.0-yocto-standard+ #1
Call Trace:
[d101dc90] [c073b264] dump_stack_lvl+0x50/0x8c (unreliable)
[d101dcb0] [c0093b70] __might_resched+0x258/0x2a8
[d101dcd0] [c0d3e634] __mutex_lock+0x6c/0x6ec
[d101dd50] [c0a84174] of_alias_get_id+0x50/0xf4
[d101dd80] [c002ec78] pcibios_alloc_controller+0x1b8/0x220
[d101ddd0] [c140c9dc] pmac_pci_init+0x198/0x784
[d101de50] [c140852c] discover_phbs+0x30/0x4c
[d101de60] [c0007fd4] do_one_initcall+0x94/0x344
[d101ded0] [c1403b40] kernel_init_freeable+0x1a8/0x22c
[d101df10] [c00086e0] kernel_init+0x34/0x160
[d101df30] [c001b334] ret_from_kernel_thread+0x5c/0x64

This is because pcibios_alloc_controller() holds hose_spinlock but
of_alias_get_id() takes of_mutex which can sleep.

The hose_spinlock protects the phb_bitmap, and also the hose_list, but
it doesn't need to be held while get_phb_number() calls the OF routines,
because those are only looking up information in the device tree.

So fix it by having get_phb_number() take the hose_spinlock itself, only
where required, and then dropping the lock before returning.
pcibios_alloc_controller() then needs to take the lock again before the
list_add() but that's safe, the order of the list is not important.

Analysis

No analysis available yet

Remediation

No remediation available yet

Tracking

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Advisories

Source ID Title
EUVD EUVD EUVD-2022-55316 In the Linux kernel, the following vulnerability has been resolved: powerpc/pci: Fix get_phb_number() locking The recent change to get_phb_number() causes a DEBUG_ATOMIC_SLEEP warning on some systems: BUG: sleeping function called from invalid context at kernel/locking/mutex.c:580 in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 1, name: swapper preempt_count: 1, expected: 0 RCU nest depth: 0, expected: 0 1 lock held by swapper/1: #0: c157efb0 (hose_spinlock){+.+.}-{2:2}, at: pcibios_alloc_controller+0x64/0x220 Preemption disabled at: [<00000000>] 0x0 CPU: 0 PID: 1 Comm: swapper Not tainted 5.19.0-yocto-standard+ #1 Call Trace: [d101dc90] [c073b264] dump_stack_lvl+0x50/0x8c (unreliable) [d101dcb0] [c0093b70] __might_resched+0x258/0x2a8 [d101dcd0] [c0d3e634] __mutex_lock+0x6c/0x6ec [d101dd50] [c0a84174] of_alias_get_id+0x50/0xf4 [d101dd80] [c002ec78] pcibios_alloc_controller+0x1b8/0x220 [d101ddd0] [c140c9dc] pmac_pci_init+0x198/0x784 [d101de50] [c140852c] discover_phbs+0x30/0x4c [d101de60] [c0007fd4] do_one_initcall+0x94/0x344 [d101ded0] [c1403b40] kernel_init_freeable+0x1a8/0x22c [d101df10] [c00086e0] kernel_init+0x34/0x160 [d101df30] [c001b334] ret_from_kernel_thread+0x5c/0x64 This is because pcibios_alloc_controller() holds hose_spinlock but of_alias_get_id() takes of_mutex which can sleep. The hose_spinlock protects the phb_bitmap, and also the hose_list, but it doesn't need to be held while get_phb_number() calls the OF routines, because those are only looking up information in the device tree. So fix it by having get_phb_number() take the hose_spinlock itself, only where required, and then dropping the lock before returning. pcibios_alloc_controller() then needs to take the lock again before the list_add() but that's safe, the order of the list is not important.
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Weaknesses CWE-667
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:5.10.137:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.0:rc1:*:*:*:*:*:*
Metrics cvssV3_1

{'score': 2.5, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L'}

cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}

Type Values Removed Values Added
Weaknesses CWE-413
Metrics cvssV3_1

{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}

threat_severity

Moderate

cvssV3_1

{'score': 2.5, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L'}

threat_severity

Low

Type Values Removed Values Added
References
Metrics threat_severity

None

cvssV3_1

{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}

threat_severity

Moderate

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: powerpc/pci: Fix get_phb_number() locking The recent change to get_phb_number() causes a DEBUG_ATOMIC_SLEEP warning on some systems: BUG: sleeping function called from invalid context at kernel/locking/mutex.c:580 in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 1, name: swapper preempt_count: 1, expected: 0 RCU nest depth: 0, expected: 0 1 lock held by swapper/1: #0: c157efb0 (hose_spinlock){+.+.}-{2:2}, at: pcibios_alloc_controller+0x64/0x220 Preemption disabled at: [<00000000>] 0x0 CPU: 0 PID: 1 Comm: swapper Not tainted 5.19.0-yocto-standard+ #1 Call Trace: [d101dc90] [c073b264] dump_stack_lvl+0x50/0x8c (unreliable) [d101dcb0] [c0093b70] __might_resched+0x258/0x2a8 [d101dcd0] [c0d3e634] __mutex_lock+0x6c/0x6ec [d101dd50] [c0a84174] of_alias_get_id+0x50/0xf4 [d101dd80] [c002ec78] pcibios_alloc_controller+0x1b8/0x220 [d101ddd0] [c140c9dc] pmac_pci_init+0x198/0x784 [d101de50] [c140852c] discover_phbs+0x30/0x4c [d101de60] [c0007fd4] do_one_initcall+0x94/0x344 [d101ded0] [c1403b40] kernel_init_freeable+0x1a8/0x22c [d101df10] [c00086e0] kernel_init+0x34/0x160 [d101df30] [c001b334] ret_from_kernel_thread+0x5c/0x64 This is because pcibios_alloc_controller() holds hose_spinlock but of_alias_get_id() takes of_mutex which can sleep. The hose_spinlock protects the phb_bitmap, and also the hose_list, but it doesn't need to be held while get_phb_number() calls the OF routines, because those are only looking up information in the device tree. So fix it by having get_phb_number() take the hose_spinlock itself, only where required, and then dropping the lock before returning. pcibios_alloc_controller() then needs to take the lock again before the list_add() but that's safe, the order of the list is not important.
Title powerpc/pci: Fix get_phb_number() locking
References
Weaknesses

Sources

Status
PUBLISHED
Assigner
Linux
Published
Updated
Nov 5, 2026, 8:00 PM
Reserved
Jun 18, 2025, 10:57 AM
Status
Analyzed
Published
Jun 18, 2025, 11:15 AM
Modified
Nov 5, 2026, 8:17 PM
Severity
Low
Public date
Jun 18, 2025, 12:00 AM