Description
In the Linux kernel, the following vulnerability has been resolved: mm/page_alloc: fix race condition in unaccepted memory handling The page allocator tracks the number of zones that have unaccepted memory using static_branch_enc/dec() and uses that static branch in hot paths to determine if it needs to deal with unaccepted memory. Borislav and Thomas pointed out that the tracking is racy: operations on static_branch are not serialized against adding/removing unaccepted pages to/from the zone. Sanity checks inside static_branch machinery detects it: WARNING: CPU: 0 PID: 10 at kernel/jump_label.c:276 __static_key_slow_dec_cpuslocked+0x8e/0xa0 The comment around the WARN() explains the problem: /* * Warn about the '-1' case though; since that means a * decrement is concurrent with a first (0->1) increment. IOW * people are trying to disable something that wasn't yet fully * enabled. This suggests an ordering problem on the user side. */ The effect of this static_branch optimization is only visible on microbenchmark. Instead of adding more complexity around it, remove it altogether.
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
dcdfdd40fa82b6704d2841938e5c8ec3051eb0d6 to < 98fdd2f612e949c652693f6df00442c81037776daffecteddcdfdd40fa82b6704d2841938e5c8ec3051eb0d6 to < 74953f93f47a45296cc2a3fd04e2a3202ff3fa53affecteddcdfdd40fa82b6704d2841938e5c8ec3051eb0d6 to < 71dda1cb10702dc2859f00eb789b0502de2176a9affecteddcdfdd40fa82b6704d2841938e5c8ec3051eb0d6 to < fefc075182275057ce607effaa3daa9e6e3bdc73affected
Linux Linux
Default version status: affected
6.5affected0 to < 6.5unaffected6.6.92 to ≤ 6.6.*unaffected6.12.30 to ≤ 6.12.*unaffected6.14.8 to ≤ 6.14.*unaffected6.15 to ≤ *unaffected