138 lines
8.9 KiB
JSON
138 lines
8.9 KiB
JSON
{
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"dataType": "CVE_RECORD",
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"dataVersion": "5.2",
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"cveMetadata": {
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"cveId": "CVE-2026-43385",
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"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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"state": "PUBLISHED",
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"assignerShortName": "Linux",
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"dateReserved": "2026-05-01T14:12:56.006Z",
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"datePublished": "2026-05-08T14:21:32.007Z",
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"dateUpdated": "2026-08-05T12:27:43.989Z"
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},
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"containers": {
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"cna": {
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"providerMetadata": {
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"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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"shortName": "Linux",
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"dateUpdated": "2026-08-05T12:27:43.989Z"
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},
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"descriptions": [
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{
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"lang": "en",
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: Fix rcu_tasks stall in threaded busypoll\n\nI was debugging a NIC driver when I noticed that when I enable\nthreaded busypoll, bpftrace hangs when starting up. dmesg showed:\n\n rcu_tasks_wait_gp: rcu_tasks grace period number 85 (since boot) is 10658 jiffies old.\n rcu_tasks_wait_gp: rcu_tasks grace period number 85 (since boot) is 40793 jiffies old.\n rcu_tasks_wait_gp: rcu_tasks grace period number 85 (since boot) is 131273 jiffies old.\n rcu_tasks_wait_gp: rcu_tasks grace period number 85 (since boot) is 402058 jiffies old.\n INFO: rcu_tasks detected stalls on tasks:\n 00000000769f52cd: .N nvcsw: 2/2 holdout: 1 idle_cpu: -1/64\n task:napi/eth2-8265 state:R running task stack:0 pid:48300 tgid:48300 ppid:2 task_flags:0x208040 flags:0x00004000\n Call Trace:\n <TASK>\n ? napi_threaded_poll_loop+0x27c/0x2c0\n ? __pfx_napi_threaded_poll+0x10/0x10\n ? napi_threaded_poll+0x26/0x80\n ? kthread+0xfa/0x240\n ? __pfx_kthread+0x10/0x10\n ? ret_from_fork+0x31/0x50\n ? __pfx_kthread+0x10/0x10\n ? ret_from_fork_asm+0x1a/0x30\n </TASK>\n\nThe cause is that in threaded busypoll, the main loop is in\nnapi_threaded_poll rather than napi_threaded_poll_loop, where the\nlatter rarely iterates more than once within its loop. For\nrcu_softirq_qs_periodic inside napi_threaded_poll_loop to report its\nqs state, the last_qs must be 100ms behind, and this can't happen\nbecause napi_threaded_poll_loop rarely iterates in threaded busypoll,\nand each time napi_threaded_poll_loop is called last_qs is reset to\nlatest jiffies.\n\nThis patch changes so that in threaded busypoll, last_qs is saved\nin the outer napi_threaded_poll, and whether busy_poll_last_qs\nis NULL indicates whether napi_threaded_poll_loop is called for\nbusypoll. This way last_qs would not reset to latest jiffies on\neach invocation of napi_threaded_poll_loop."
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}
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],
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"metrics": [
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{
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"cvssV3_1": {
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"version": "3.1",
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"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
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"baseScore": 7.5,
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"baseSeverity": "HIGH"
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},
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"scenarios": [
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{
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"lang": "en",
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"value": "AV:N - In a reasonable high-impact deployment, threaded NAPI busy-poll is enabled on a network-facing NIC/forwarder, and received packets schedule the NAPI kthread into the vulnerable polling loop. The netlink knob is an administrative deployment gate, but a remote sender needs no local access once that mode is in use.\nAC:L - There is no attacker-controlled race or fragile timing requirement; once the NAPI thread is in threaded busy-poll mode, repeated loop invocations reliably fail to report RCU Tasks quiescent states. Packet delivery to the configured NAPI is sufficient to activate the path.\nPR:N - The highest-impact scenario is an already-configured network service/device where the attacker only sends packets and needs no account or credentials. Enabling threaded busy-poll itself requires init-namespace CAP_NET_ADMIN, but that is a deployment precondition rather than an exploit privilege in this scenario.\nUI:N - No victim user action is required after the affected NAPI mode is configured. Network traffic alone can keep the vulnerable kthread path active.\nS:U - The impact remains within the kernel and host networking/RCU scheduling authority. There is no VM escape, sandbox boundary crossing, or separate security authority affected.\nC:N - The bug is an RCU Tasks quiescent-state starvation/stall, not memory corruption or an information disclosure path. I found no read primitive or exposure of protected data.\nI:N - The flaw does not provide an arbitrary write, control-flow hijack, or data modification primitive. It only prevents timely RCU Tasks grace-period progress.\nA:H - The vulnerable loop can indefinitely stall RCU Tasks grace periods, causing kernel operations such as tracing/BPF setup or teardown to hang and producing persistent RCU stall reports. This is a kernel-level hang/deadlock-style availability failure."
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}
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]
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}
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],
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"affected": [
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{
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"product": "Linux",
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"vendor": "Linux",
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"defaultStatus": "unaffected",
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"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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"programFiles": [
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"net/core/dev.c"
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],
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"versions": [
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{
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"version": "c18d4b190a46651726c9a952667c74d2deb33c28",
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"lessThan": "52459201d0df3fdbb1d281738b7b772e2cacb49c",
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"status": "affected",
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"versionType": "git"
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"lessThan": "1a86a1f7d88996085934139fa4c063b6299a2dd3",
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"status": "affected",
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}
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]
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},
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{
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"product": "Linux",
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"vendor": "Linux",
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"defaultStatus": "affected",
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"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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"programFiles": [
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"net/core/dev.c"
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],
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"versions": [
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{
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"version": "6.19",
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"status": "affected"
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},
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{
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"version": "0",
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"lessThan": "6.19",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.19.9",
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"lessThanOrEqual": "6.19.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "7.0",
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"lessThanOrEqual": "*",
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"status": "unaffected",
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"versionType": "original_commit_for_fix"
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}
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]
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}
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],
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"cpeApplicability": [
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"versionStartIncluding": "6.19",
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"versionEndExcluding": "6.19.9"
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},
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{
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"vulnerable": true,
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "6.19",
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}
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}
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]
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}
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],
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"references": [
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{
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"url": "https://git.kernel.org/stable/c/52459201d0df3fdbb1d281738b7b772e2cacb49c"
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},
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{
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"url": "https://git.kernel.org/stable/c/1a86a1f7d88996085934139fa4c063b6299a2dd3"
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}
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],
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"title": "net: Fix rcu_tasks stall in threaded busypoll",
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