Linux vulnerability

What happened

In the Linux kernel, the following vulnerability has been resolved: KVM: arm64: vgic-its: Drop the translation cache reference only for the erased entry vgic_its_invalidate_cache() walks the per-ITS translation cache with xa_for_each() and drops the cache's reference on each entry with vgic_put_irq(). It puts the iterated pointer, though, rather than the value returned by xa_erase(). The function is called from contexts that do not exclude one another: the ITS command handlers hold its_lock, the GITS_CTLR write path holds cmd_lock, and the path that clears EnableLPIs in a redistributor's GICR_CTLR holds neither. Two or more of them can drain the same cache concurrently, and if each one observes the same entry, erases it and then puts it, the single reference the cache holds on that entry is dropped more than once. The entry can then be freed while an ITE still maps it. xa_erase() is atomic and returns the previous entry, so put only the entry that this context actually removed. The cache reference is then dropped exactly once per entry even when the invalidations run concurrently, and the behavior is unchanged when only one context runs.

Affected versions

Linux: 8201d1028caa4fae88e222c4e8cf541fdf45b821 through before b7b72e88046328c9fdc638fe887d4240257dd5dc (git); 8201d1028caa4fae88e222c4e8cf541fdf45b821 through before 2bbc395e81bd29c543a0529a678327e932a7ec69 (git); 8201d1028caa4fae88e222c4e8cf541fdf45b821 through before 9121f4605ab94969f62d1b5714ca3c6c69bd202f (git); 8201d1028caa4fae88e222c4e8cf541fdf45b821 through before 13031fb6b8357fbbcded2a7f4cba73e4781ee594 (git); 6.10 Fixed: See vendor advisory.

Why it matters

Review the vendor advisory and exposure of the affected product to determine operational impact.

Detection & mitigation

• Apply vendor-provided updates or mitigations.
• Review affected product exposure and access logs.