Affected: Linux

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

PCI: vmd: Make vmd_dev::cfg_lock a raw_spinlock_t type

The access to the PCI config space via pci_ops::read and pci_ops::write is a low-level hardware access. The functions can be accessed with disabled interrupts even on PREEMPT_RT. The pci_lock is a raw_spinlock_t for this purpose.

A spinlock_t becomes a sleeping lock on PREEMPT_RT, so it cannot be acquired with disabled interrupts. The vmd_dev::cfg_lock is accessed in the same context as the pci_lock.

Make vmd_dev::cfg_lock a raw_spinlock_t type so it can be used with interrupts disabled.

This was reported as:

BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48 Call Trace: rt_spin_lock+0x4e/0x130 vmd_pci_read+0x8d/0x100 [vmd] pci_user_read_config_byte+0x6f/0xe0 pci_read_config+0xfe/0x290 sysfs_kf_bin_read+0x68/0x90

[bigeasy: reword commit message] Tested-off-by: Luis Claudio R. Goncalves <lgoncalv@redhat.com> [kwilczynski: commit log] [bhelgaas: add back report info from https://lore.kernel.org/lkml/20241218115951.83062-1-ryotkkr98@gmail.com/]