Improper Locking Affecting kernel-debug-modules package, versions *

Note: Versions mentioned in the description apply only to the upstream kernel-debug-modules package and not the kernel-debug-modules package as distributed by Centos. See How to fix? for Centos:8 relevant fixed versions and status.

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

drm/amdgpu: handle the case of pci_channel_io_frozen only in amdgpu_pci_resume

In current code, when a PCI error state pci_channel_io_normal is detectd, it will report PCI_ERS_RESULT_CAN_RECOVER status to PCI driver, and PCI driver will continue the execution of PCI resume callback report_resume by pci_walk_bridge, and the callback will go into amdgpu_pci_resume finally, where write lock is releasd unconditionally without acquiring such lock first. In this case, a deadlock will happen when other threads start to acquire the read lock.

To fix this, add a member in amdgpu_device strucutre to cache pci_channel_state, and only continue the execution in amdgpu_pci_resume when it's pci_channel_io_frozen.

• https://access.redhat.com/security/cve/CVE-2021-47421
• https://git.kernel.org/stable/c/248b061689a40f4fed05252ee2c89f87cf26d7d8
• https://git.kernel.org/stable/c/72e9a1bf9b722628c28092e0c2cd8717edd201dc