CVE-2026-90201
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.
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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:
The scrub path calls __page_pool_unmap_netmem_dma() directly; the return path calls __page_pool_release_netmem_dma().
Detalles técnicos trazas, registros y código del informe original
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).
CVSS
NVD no ha asignado puntuación CVSS a esta CVE (habitual desde el cambio de política de abril de 2026).
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.21%
- Percentil entre todas las CVEs puntuadas: 10
- Fecha de la puntuación: 4/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
Tecnologías afectadas (1)
⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.
Referencias
JSON original (NVD)
Mostrar
{
"id": "CVE-2026-90201",
"cveTags": [],
"metrics": {},
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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"published": "2026-09-17T17:17:15.053",
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{
"url": "https://git.kernel.org/stable/c/24ef02f934eeb48830cff6b739abc3c62b1d107b",
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"vulnStatus": "Received",
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: page_pool: fix UAF in __page_pool_release_netmem_dma on xa_cmpxchg race\n\nThis bug was discovered while testing the hns3 driver under channel\nreconfiguration (`ethtool -L` / `ethtool -G`) with iperf3 traffic on\narm64. The race is intermittently triggered when page_pool_destroy()\nruns page_pool_scrub() concurrently with page return via\npage_pool_put_netmem() on a different CPU. A WARN in\npage_pool_clear_pp_info() surfaced the dangling DMA index bits left\nby the cmpxchg loser, which led to the investigation.\n\npage_pool_scrub() iterates pool->dma_mapped via xa_for_each() with no\npage ref held. __page_pool_release_netmem_dma() currently reads and\nwrites netmem fields (dma_addr, DMA index bits in pp_magic) after\nxa_cmpxchg() returns. The unref path calls put_page() unconditionally\nregardless of the cmpxchg outcome; when it loses the cmpxchg, it still\nfrees the page before the scrub winner finishes these netmem accesses,\nso scrub touches a freed page -- a Use-After-Free.\n\nFix this by splitting the DMA release into two functions:\n\n1. __page_pool_unmap_netmem_dma() caches dma_addr before xa_cmpxchg(),\n does the cmpxchg to remove the DMA mapping, and calls dma_unmap on\n the cached address. It never touches netmem fields after the cmpxchg,\n making it safe for the scrub path which holds no page ref.\n\n2. __page_pool_release_netmem_dma() wraps the above and additionally\n clears dma_addr and DMA index bits in netmem fields. This is safe\n only when the caller holds a page ref, so it is used by the return\n path (page_pool_return_netmem).\n\nThe scrub path calls __page_pool_unmap_netmem_dma() directly; the return\npath calls __page_pool_release_netmem_dma()."
}
],
"lastModified": "2026-09-17T17:17:15.053",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}