CVE-2025-68169
In the Linux kernel, the following vulnerability has been resolved:
netpoll: Fix deadlock in memory allocation under spinlock
Fix a AA deadlock in refill_skbs() where memory allocation while holding skb_pool->lock can trigger a recursive lock acquisition attempt.
The deadlock scenario occurs when the system is under severe memory pressure:
1. refill_skbs() acquires skb_pool->lock (spinlock) 2. alloc_skb() is called while holding the lock 3. Memory allocator fails and calls slab_out_of_memory() 4. This triggers printk() for the OOM warning 5. The console output path calls netpoll_send_udp() 6. netpoll_send_udp() attempts to acquire the same skb_pool->lock 7. Deadlock: the lock is already held by the same CPU
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This bug was exposed by commit 248f6571fd4c51 ("netpoll: Optimize skb refilling on critical path") which removed refill_skbs() from the critical path (where nested printk was being deferred), letting nested printk being called from inside refill_skbs()
Refactor refill_skbs() to never allocate memory while holding the spinlock.
Another possible solution to fix this problem is protecting the refill_skbs() from nested printks, basically calling printk_deferred_{enter,exit}() in refill_skbs(), then, any nested pr_warn() would be deferred.
I prefer this approach, given I _think_ it might be a good idea to move the alloc_skb() from GFP_ATOMIC to GFP_KERNEL in the future, so, having the alloc_skb() outside of the lock will be necessary step.
There is a possible TOCTOU issue when checking for the pool length, and queueing the new allocated skb, but, this is not an issue, given that an extra SKB in the pool is harmless and it will be eventually used.
Detalles técnicos trazas, registros y código del informe original
Call stack:
refill_skbs()
spin_lock_irqsave(&skb_pool->lock) <- lock acquired
__alloc_skb()
kmem_cache_alloc_node_noprof()
slab_out_of_memory()
printk()
console_flush_all()
netpoll_send_udp()
skb_dequeue()
spin_lock_irqsave(&skb_pool->lock) <- deadlock attemptCVSS
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: 0.19%
- Percentil entre todas las CVEs puntuadas: 8
- Fecha de la puntuación: 6/10/2026
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)
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{
"id": "CVE-2025-68169",
"cveTags": [],
"metrics": {},
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "248f6571fd4c51531f7f8f07f186f7ae98a50afc",
"lessThan": "06742a3ab884d7428c9050b205ffcf6a8a548397",
"versionType": "git"
},
{
"status": "affected",
"version": "248f6571fd4c51531f7f8f07f186f7ae98a50afc",
"lessThan": "327c20c21d80e0d87834b392d83ae73c955ad8ff",
"versionType": "git"
}
],
"programFiles": [
"net/core/netpoll.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "6.15"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "6.15",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.17.8",
"versionType": "semver",
"lessThanOrEqual": "6.17.*"
},
{
"status": "unaffected",
"version": "6.18",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"net/core/netpoll.c"
],
"defaultStatus": "affected"
}
]
}
],
"published": "2025-12-16T14:15:48.760",
"references": [
{
"url": "https://git.kernel.org/stable/c/06742a3ab884d7428c9050b205ffcf6a8a548397",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/327c20c21d80e0d87834b392d83ae73c955ad8ff",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"vulnStatus": "Deferred",
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetpoll: Fix deadlock in memory allocation under spinlock\n\nFix a AA deadlock in refill_skbs() where memory allocation while holding\nskb_pool->lock can trigger a recursive lock acquisition attempt.\n\nThe deadlock scenario occurs when the system is under severe memory\npressure:\n\n1. refill_skbs() acquires skb_pool->lock (spinlock)\n2. alloc_skb() is called while holding the lock\n3. Memory allocator fails and calls slab_out_of_memory()\n4. This triggers printk() for the OOM warning\n5. The console output path calls netpoll_send_udp()\n6. netpoll_send_udp() attempts to acquire the same skb_pool->lock\n7. Deadlock: the lock is already held by the same CPU\n\nCall stack:\n refill_skbs()\n spin_lock_irqsave(&skb_pool->lock) <- lock acquired\n __alloc_skb()\n kmem_cache_alloc_node_noprof()\n slab_out_of_memory()\n printk()\n console_flush_all()\n netpoll_send_udp()\n skb_dequeue()\n spin_lock_irqsave(&skb_pool->lock) <- deadlock attempt\n\nThis bug was exposed by commit 248f6571fd4c51 (\"netpoll: Optimize skb\nrefilling on critical path\") which removed refill_skbs() from the\ncritical path (where nested printk was being deferred), letting nested\nprintk being called from inside refill_skbs()\n\nRefactor refill_skbs() to never allocate memory while holding\nthe spinlock.\n\nAnother possible solution to fix this problem is protecting the\nrefill_skbs() from nested printks, basically calling\nprintk_deferred_{enter,exit}() in refill_skbs(), then, any nested\npr_warn() would be deferred.\n\nI prefer this approach, given I _think_ it might be a good idea to move\nthe alloc_skb() from GFP_ATOMIC to GFP_KERNEL in the future, so, having\nthe alloc_skb() outside of the lock will be necessary step.\n\nThere is a possible TOCTOU issue when checking for the pool length, and\nqueueing the new allocated skb, but, this is not an issue, given that\nan extra SKB in the pool is harmless and it will be eventually used."
}
],
"lastModified": "2026-06-17T09:58:40.477",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}