CVEvulnerability
CVE-2026-93239
- Status
- Received
- Published
- 2026-09-24
- Last modified
- 2026-10-19
- Assigner
- 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Description
In the Linux kernel, the following vulnerability has been resolved:
arm64: mm: Fix the lockless page-table walk in show_pte()
show_pte() walks page tables locklessly and can run with interrupts
enabled. A concurrent teardown can free a table page while it is being
walked. It can also clear a parent entry after show_pte() checked it; the
regular pXd_offset() helpers then reread the cleared entry and can derive a
bogus lower-level pointer and fault again.
Use the lockless offset helpers with the saved parent entries, as
gup_fast() does, and pass the saved PMD to pte_offset_map().
For task page tables, arm64 selects MMU_GATHER_RCU_TABLE_FREE. Disable
local interrupts around the walk to hold off RCU-deferred table frees and
block the tlb_remove_table_sync_one() IPI until the walk is finished.
Place the IRQ guard after the header print. This does not make the output a
consistent snapshot, but prevents the task page-table walk from
dereferencing a released table page or deriving a pointer from a different
parent value.
References
- https://git.kernel.org/stable/c/08d931a0a850ad16a64f2cd23a19f40795cdbdf7 git.kernel.org
- https://git.kernel.org/stable/c/0f05d95b99164a9ccc4cf4a4920e0ff0228138ad git.kernel.org
- https://git.kernel.org/stable/c/68cbd70795dd8c06e7ccdc4eb0b74c5b180076c3 git.kernel.org
- https://git.kernel.org/stable/c/a77644d009dece1104b6fcc6e322b0e4503db0d6 git.kernel.org
- https://git.kernel.org/stable/c/b28fe65a36b8209b6adcf2722c7ce974cf9ac8d1 git.kernel.org