x86/amd_node: Fix potential NULL pointer dereference

Summary

In the Linux kernel, the following vulnerability has been resolved: x86/amd_node: Fix potential NULL pointer dereference amd_smn_read/write() are exported functions around __amd_smn_rw(), so they are always available even if amd_smn_init() fails. In that case, 'amd_roots' is NULL and __amd_smn_rw() will access uninitialized memory. Then, commit: 83518453074d ("x86/amd_node: Add SMN offsets to exclusive region access") added the 'smn_exclusive' flag, which indicated the calls to pci_request_config_region_exclusive() succeeded, to prevent concurrent userspace access. Commit: 0a4b61d9c2e4 ("x86/amd_node: Fix AMD root device caching") re-ordered initialization so pci_request_config_region_exclusive() is called earlier and a failure exits amd_smn_init() before allocating 'amd_roots'. The setting of 'smn_exclusive' moved to the end of amd_smn_init(), after 'amd_roots' is allocated. It became redundant and can be removed. Replace 'smn_exclusive' with directly checking 'amd_roots', to fix a potential NULL pointer dereference and to simplify the logic. [ bp: Reorg commit message, touchup comment. ] [ mingo: Rebase & further touchups. ]

Timeline

1. Sep 25, 2026, 10:22 AM UTCCVE published
2. Oct 19, 2026, 9:11 AM UTCRecord last updated

Affected versions

• Linux Linux

  From 77466b798d59d6761501ff36094cf430d3876549 · fixed in fcd19bc829eca237742a3b123f839ad1c473ec85; From 77466b798d59d6761501ff36094cf430d3876549 · fixed in a797a2331e5d2ecdbccbae222ea71c759fdb2c2b; From 77466b798d59d6761501ff36094cf430d3876549 · fixed in aefdbd574a362dcf7569bada6d72f64a006b9fb9

• Linux Linux

  6.14

• KernelLinux

  From 6.14.0 · fixed in 6.18.53; From 6.19.0 · fixed in 7.2.7

References 3