---
cve: "CVE-2026-90201"
severity: "LOW"
cvss: 3.1
epss: "5.9%"
vendor: "Linux"
kev: false
exploited: false
published: "2026-09-17 17:17:15"
tags: [cve, security, low]
source: tsecurity.de CVE-Dossier
exported: "2026-09-20T23:59:18+02:00"
---

# CVE-2026-90201

> 3.1 LOW

## Beschreibung

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().

## Patch verfügbar (OSV)

- Kernel ≥ 6.12.110
- Kernel ≥ 6.18.52
- Kernel ≥ 7.2.6

## Referenzen

- <https://git.kernel.org/stable/c/24ef02f934eeb48830cff6b739abc3c62b1d107b>
- <https://git.kernel.org/stable/c/424a9fc4876cc7f28e9cb0aa8d92e920d726e350>
- <https://git.kernel.org/stable/c/9b65b0253ad5a66f73efee9a79a21a1e2b57cf59>
- <https://git.kernel.org/stable/c/bbfef303f980c1c078b8fa142e10a0e2fbcdd247>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-90201) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_