Description
In the Linux kernel, the following vulnerability has been resolved: KVM: arm64: Handle negative S1 walk levels in VNCR TLB size evaluation Computing the effects of a TLB invalidation involves looking at the size of the mapping cached by the TLB. For S1 mappings such as VNCR, this is deducted from the combination of the base granule size and the mapping level. However, this implies that the S1 MMU is *on*. When the MMU is off, we indicate this with the level being set to a "creative" value of -127 (S1_MMU_DISABLED). This ends-up being misinterpreted by pgshift_level_to_ttl() as it doesn't handle negative levels at all (the level is immediately cast to a u8 and only the bottom two bits considered), leading to an invalidation size of 0. Not helpful. Tidy-up pgshift_level_to_ttl() to handle these negative levels, and ttl_to_size() to always return SZ_1G when no valid TTL is present. This allows the removal of open-coded checks for similar situations. Note that the check for a negative value not explicitely checking for S1_MMU_DISABLED is deliberate, so that actual negative levels introduced with LVA2 and D128 can take the same path if we ever support them.
Affected products
Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.
Linux Linux
Default version status: unaffected
7270cc9157f474dfc46750a34c9d7defc686b2eb to < be54a70067c7dbe1381157e8a238fa4b16ea9c05affected7270cc9157f474dfc46750a34c9d7defc686b2eb to < 1c9fca34b9625a67a7f1a03c8604f3df760c6c49affected7270cc9157f474dfc46750a34c9d7defc686b2eb to < 8053393680d4fa3eb962667d2be95dd39f0940e5affected
Linux Linux
Default version status: affected
6.16affected0 to < 6.16unaffected6.18.51 to ≤ 6.18.*unaffected7.2.5 to ≤ 7.2.*unaffected7.3 to ≤ *unaffected