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CVE-2026-90201 Affecting linux-6.12 package, versions <6.12.111-1~deb12u1

Severity

 Recommended
low

Based on default assessment until relevant scores are available.

Threat Intelligence

EPSS
0.21% (10th percentile)

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  • Snyk IDSNYK-DEBIAN12-LINUX612-20507196
  • published5 Oct 2026
  • disclosed17 Sept 2026
Report a new vulnerability Found a mistake?

Introduced: 17 Sep 2026

NewCVE-2026-90201  (opens in a new tab)

How to fix?

Upgrade Debian:12 linux-6.12 to version 6.12.111-1~deb12u1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream linux-6.12 package and not the linux-6.12 package as distributed by Debian. See How to fix? for Debian:12 relevant fixed versions and status.

In the Linux kernel, the following vulnerability has been resolved:

net: page_pool: fix UAF in __page_pool_release_netmem_dma on xa_cmpxchg race

This bug was discovered while testing the hns3 driver under channel reconfiguration (ethtool -L / ethtool -G) with iperf3 traffic on arm64. The race is intermittently triggered when page_pool_destroy() runs page_pool_scrub() concurrently with page return via page_pool_put_netmem() on a different CPU. A WARN in page_pool_clear_pp_info() surfaced the dangling DMA index bits left by the cmpxchg loser, which led to the investigation.

page_pool_scrub() iterates pool->dma_mapped via xa_for_each() with no page ref held. __page_pool_release_netmem_dma() currently reads and writes netmem fields (dma_addr, DMA index bits in pp_magic) after xa_cmpxchg() returns. The unref path calls put_page() unconditionally regardless of the cmpxchg outcome; when it loses the cmpxchg, it still frees the page before the scrub winner finishes these netmem accesses, so scrub touches a freed page -- a Use-After-Free.

Fix this by splitting the DMA release into two functions:

  1. __page_pool_unmap_netmem_dma() caches dma_addr before xa_cmpxchg(), does the cmpxchg to remove the DMA mapping, and calls dma_unmap on the cached address. It never touches netmem fields after the cmpxchg, making it safe for the scrub path which holds no page ref.

  2. __page_pool_release_netmem_dma() wraps the above and additionally clears dma_addr and DMA index bits in netmem fields. This is safe only when the caller holds a page ref, so it is used by the return path (page_pool_return_netmem).

The scrub path calls __page_pool_unmap_netmem_dma() directly; the return path calls __page_pool_release_netmem_dma().