Description (CNA)
In the Linux kernel, the following vulnerability has been resolved: iommu/vt-d: Clear Present bit before tearing down scalable-mode context entry device_pasid_table_teardown() zeroes the 128-bit scalable-mode context entry with context_clear_entry() while the Present bit is still set. This creates a window where the hardware can fetch a torn entry, with some fields already zeroed while Present is still set, leading to unpredictable behavior or spurious faults. The context-cache invalidation is issued only after the entry has been zeroed, and intel_pasid_free_table() then frees the PASID directory pages, so the IOMMU can keep walking a stale Present=1 entry that points at freed memory. While x86 provides strong write ordering, the compiler may reorder the two 64-bit writes to the entry, and the hardware fetch is not guaranteed to be atomic with respect to multiple CPU writes. Commit c1e4f1dccbe9d ("iommu/vt-d: Clear Present bit before tearing down context entry") fixed this exact pattern in domain_context_clear_one() and the copied-context path, but device_pasid_table_teardown() was not converted. Align it with the "Guidance to Software for Invalidations" in the VT-d spec, Section 6.5.3.3, using the same ownership handshake as the sibling fix: clear only the Present bit, flush it to the IOMMU, perform the context-cache invalidation, and only then zero the rest of the entry.
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| Linux / Linux | affected 81e921fd321614c2ad8ac333b041aae1da7a1c6d before e9e83bcfe37dc719182500dd823c03ab57d934f0; affected 81e921fd321614c2ad8ac333b041aae1da7a1c6d before 588718101e8449605f1c7e858fecb7cfa701cdab; affected 81e921fd321614c2ad8ac333b041aae1da7a1c6d before 7fd4077dc92b91b1b844333c0a06bb9e286db10a; affected 81e921fd321614c2ad8ac333b041aae1da7a1c6d before f46452c3df7a8d8a5addc0926e76ef19ea7da0a0; affected 333fe86968482ca701c609af590003bcea450e8f; affected 6.8.2 before 6.9 |
| Linux / Linux | affected 6.9; unaffected 0 before 6.9; unaffected 6.12.97 through 6.12.*; unaffected 6.18.40 through 6.18.*; unaffected 7.1.5 through 7.1.*; unaffected 7.2 through * |
CWE
No CWE identifiers supplied.
References
- https://git.kernel.org/stable/c/e9e83bcfe37dc719182500dd823c03ab57d934f0
- https://git.kernel.org/stable/c/588718101e8449605f1c7e858fecb7cfa701cdab
- https://git.kernel.org/stable/c/7fd4077dc92b91b1b844333c0a06bb9e286db10a
- https://git.kernel.org/stable/c/f46452c3df7a8d8a5addc0926e76ef19ea7da0a0
ADP enrichment
No English description supplied.
No references supplied.