CVE-2026-74266 (GCVE-0-2026-74266)
Vulnerability from cvelistv5
Published
2026-08-15 05:57
Modified
2026-08-17 05:16
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
net/sched: sch_dualpi2: Do not call qdisc_tree_reduce_backlog during peek before restoring qlen
Whenever dualpi2 drops packets during peek, it calls
qdisc_tree_reduce_backlog. An issue arises because it calls
qdisc_tree_reduce_backlog before it reincrements the qlen. If qlen drops
to zero, but peek returns an skb, the parent's qlen_notify callback will be
executed even though dualpi2 still has 1 packet on the queue and, thus,
mistakenly deactivates the parent's class which leads to a null-ptr-deref:
[ 101.427314][ T599] Oops: general protection fault, probably for non-canonical address 0xdffffc0000000009: 0000 [#1] SMP KASAN NOPTI
[ 101.427755][ T599] KASAN: null-ptr-deref in range [0x0000000000000048-0x000000000000004f]
[ 101.428048][ T599] CPU: 2 UID: 0 PID: 599 Comm: ping Not tainted 7.1.0-rc5-00284-gbce53c430ed7 #102 PREEMPT(full)
[ 101.428400][ T599] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[ 101.428608][ T599] RIP: 0010:qfq_dequeue (net/sched/sch_qfq.c:1150) sch_qfq
[ 101.428821][ T599] Code: 00 fc ff df 80 3c 02 00 0f 85 46 0c 00 00 4c 8d 73 48 48 89 9d b8 02 00 00 48 b8 00 00 00 00 00 fc ff df 4c 89 f2 48 c1 ea 03 <80> 3c 02 00 0f 85 2d 0c 00 00 48 b8 00 00 00 00 00 fc ff df 4c 8b
All code
[ 101.429348][ T599] RSP: 0018:ffff8881110df4f0 EFLAGS: 00010216
[ 101.429541][ T599] RAX: dffffc0000000000 RBX: 0000000000000000 RCX: dffffc0000000000
[ 101.429763][ T599] RDX: 0000000000000009 RSI: 00000024c0000000 RDI: ffff88811436c2b0
[ 101.429985][ T599] RBP: ffff88811436c000 R08: ffff88811436c280 R09: 1ffff11021277523
[ 101.430206][ T599] R10: 1ffff11021277526 R11: 1ffff11021277527 R12: 00000024c0000000
[ 101.430423][ T599] R13: ffff88811436c2b8 R14: 0000000000000048 R15: 0000000020000000
[ 101.430642][ T599] FS: 00007f61813e1c40(0000) GS:ffff8881691ef000(0000) knlGS:0000000000000000
[ 101.430913][ T599] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 101.431100][ T599] CR2: 00005651650850a8 CR3: 000000010ca0b000 CR4: 0000000000750ef0
[ 101.431320][ T599] PKRU: 55555554
[ 101.431433][ T599] Call Trace:
[ 101.431544][ T599] <TASK>
[ 101.431628][ T599] __qdisc_run (net/sched/sch_generic.c:322 net/sched/sch_generic.c:427 net/sched/sch_generic.c:445)
[ 101.431792][ T599] ? dev_qdisc_enqueue (./include/trace/events/qdisc.h:49 (discriminator 22) net/core/dev.c:4176 (discriminator 22))
[ 101.431941][ T599] __dev_queue_xmit (./include/net/pkt_sched.h:120 ./include/net/pkt_sched.h:117 net/core/dev.c:4292 net/core/dev.c:4831)
Fix this by only calling qdisc_tree_reduce_backlog in peek after the
qlen is restored.
References
Impacted products
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"net/sched/sch_dualpi2.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "bd851b10daee7199a658458b8ce250e95a334500",
"status": "affected",
"version": "8f9516daedd67097a0c6e463fcb7a42b5ee9d477",
"versionType": "git"
},
{
"lessThan": "466f29477cae2bd1982a066d518a9b20c5a37924",
"status": "affected",
"version": "8f9516daedd67097a0c6e463fcb7a42b5ee9d477",
"versionType": "git"
},
{
"lessThan": "15cd0c93bf4f892d66bc7a93667e2357b5673365",
"status": "affected",
"version": "8f9516daedd67097a0c6e463fcb7a42b5ee9d477",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"net/sched/sch_dualpi2.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "6.17"
},
{
"lessThan": "6.17",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.40",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.1.*",
"status": "unaffected",
"version": "7.1.5",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.18.40",
"versionStartIncluding": "6.17",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.1.5",
"versionStartIncluding": "6.17",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.2",
"versionStartIncluding": "6.17",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: sch_dualpi2: Do not call qdisc_tree_reduce_backlog during peek before restoring qlen\n\nWhenever dualpi2 drops packets during peek, it calls\nqdisc_tree_reduce_backlog. An issue arises because it calls\nqdisc_tree_reduce_backlog before it reincrements the qlen. If qlen drops\nto zero, but peek returns an skb, the parent\u0027s qlen_notify callback will be\nexecuted even though dualpi2 still has 1 packet on the queue and, thus,\nmistakenly deactivates the parent\u0027s class which leads to a null-ptr-deref:\n\n[ 101.427314][ T599] Oops: general protection fault, probably for non-canonical address 0xdffffc0000000009: 0000 [#1] SMP KASAN NOPTI\n[ 101.427755][ T599] KASAN: null-ptr-deref in range [0x0000000000000048-0x000000000000004f]\n[ 101.428048][ T599] CPU: 2 UID: 0 PID: 599 Comm: ping Not tainted 7.1.0-rc5-00284-gbce53c430ed7 #102 PREEMPT(full)\n[ 101.428400][ T599] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011\n[ 101.428608][ T599] RIP: 0010:qfq_dequeue (net/sched/sch_qfq.c:1150) sch_qfq\n[ 101.428821][ T599] Code: 00 fc ff df 80 3c 02 00 0f 85 46 0c 00 00 4c 8d 73 48 48 89 9d b8 02 00 00 48 b8 00 00 00 00 00 fc ff df 4c 89 f2 48 c1 ea 03 \u003c80\u003e 3c 02 00 0f 85 2d 0c 00 00 48 b8 00 00 00 00 00 fc ff df 4c 8b\nAll code\n[ 101.429348][ T599] RSP: 0018:ffff8881110df4f0 EFLAGS: 00010216\n[ 101.429541][ T599] RAX: dffffc0000000000 RBX: 0000000000000000 RCX: dffffc0000000000\n[ 101.429763][ T599] RDX: 0000000000000009 RSI: 00000024c0000000 RDI: ffff88811436c2b0\n[ 101.429985][ T599] RBP: ffff88811436c000 R08: ffff88811436c280 R09: 1ffff11021277523\n[ 101.430206][ T599] R10: 1ffff11021277526 R11: 1ffff11021277527 R12: 00000024c0000000\n[ 101.430423][ T599] R13: ffff88811436c2b8 R14: 0000000000000048 R15: 0000000020000000\n[ 101.430642][ T599] FS: 00007f61813e1c40(0000) GS:ffff8881691ef000(0000) knlGS:0000000000000000\n[ 101.430913][ T599] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n[ 101.431100][ T599] CR2: 00005651650850a8 CR3: 000000010ca0b000 CR4: 0000000000750ef0\n[ 101.431320][ T599] PKRU: 55555554\n[ 101.431433][ T599] Call Trace:\n[ 101.431544][ T599] \u003cTASK\u003e\n[ 101.431628][ T599] __qdisc_run (net/sched/sch_generic.c:322 net/sched/sch_generic.c:427 net/sched/sch_generic.c:445)\n[ 101.431792][ T599] ? dev_qdisc_enqueue (./include/trace/events/qdisc.h:49 (discriminator 22) net/core/dev.c:4176 (discriminator 22))\n[ 101.431941][ T599] __dev_queue_xmit (./include/net/pkt_sched.h:120 ./include/net/pkt_sched.h:117 net/core/dev.c:4292 net/core/dev.c:4831)\n\nFix this by only calling qdisc_tree_reduce_backlog in peek after the\nqlen is restored."
}
],
"providerMetadata": {
"dateUpdated": "2026-08-17T05:16:08.881Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/bd851b10daee7199a658458b8ce250e95a334500"
},
{
"url": "https://git.kernel.org/stable/c/466f29477cae2bd1982a066d518a9b20c5a37924"
},
{
"url": "https://git.kernel.org/stable/c/15cd0c93bf4f892d66bc7a93667e2357b5673365"
}
],
"title": "net/sched: sch_dualpi2: Do not call qdisc_tree_reduce_backlog during peek before restoring qlen",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-74266",
"datePublished": "2026-08-15T05:57:41.611Z",
"dateReserved": "2026-08-15T05:44:03.878Z",
"dateUpdated": "2026-08-17T05:16:08.881Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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