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amt: send the relay's General Query directly from the receive path

Type: advisorySource: Official CVE List1 source record

In the Linux kernel, the following vulnerability has been resolved: amt: send the relay's General Query directly from the receive path An skb queued in a qdisc can outlive the tunnel it references through a raw pointer in skb->cb. For example, with igmp_qrv set to 1 on the relay a tunnel lives for 135s, so a netem delay of 180s on the amt device outlives it; when the tunnel expires and is freed, the subsequent dequeue triggers a use-after-free in amt_dev_xmit(). BUG: KASAN: slab-use-after-free in amt_dev_xmit+0x2763/0x2e20 Call Trace: amt_dev_xmit+0x2763/0x2e20 [drivers/net/amt.c:1262] dev_hard_start_xmit+0x22f/0x620 sch_direct_xmit+0x12e/0xac0 netem_dequeue+0x333/0xc50 net_tx_action+0x35c/0xa60 amt_send_igmp_gq() and amt_send_mld_gq() are only called from amt_request_handler(), inside the rcu_read_lock_bh() section of amt_rcv(). amt_request_handler() already has the tunnel the query is for: it found or created it inside that section. Queuing the query with dev_queue_xmit() only leads back into amt_dev_xmit(), which strips the Ethernet header and calls amt_send_membership_query() for that tunnel. Make that call directly from the two senders instead, the same way amt_send_advertisement() transmits from the receive path. The query never waits in a qdisc, the tunnel is only dereferenced inside the RCU section that found or created it, and nothing is stored in skb->cb, so no lookup or refcount is needed. Remove the query branch of amt_dev_xmit(), amt_skb_cb() and struct amt_skb_c

Announced Source revision 1
Original source ↗

CVE-2026-98968

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2026-98968

Linux

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
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Prerequisites
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Linux

Source reference: /containers/cna/affected/1/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "cbc21dc1cfe949e37b2a54c71511579f1899e8d4",
        "lessThan": "95114e421196250e3d9662f12df442799477d3c3",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "cbc21dc1cfe949e37b2a54c71511579f1899e8d4",
        "lessThan": "e7183b7d518ce8b3e1f7284f9881d7a87569df14",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "cbc21dc1cfe949e37b2a54c71511579f1899e8d4",
        "lessThan": "181cb48c1e9af6b402567e132f879f89d1c54131",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "cbc21dc1cfe949e37b2a54c71511579f1899e8d4",
        "lessThan": "e7ea63b4195a150604993044ab574d8240f2a399",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "cbc21dc1cfe949e37b2a54c71511579f1899e8d4",
        "lessThan": "afae89de73dd693cfa329580ba0fba63bd3f0a11",
        "versionType": "git"
      }
    ],
    "programFiles": [
      "drivers/net/amt.c",
      "include/net/amt.h"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "5.16"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "5.16",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "6.6.160",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.113",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.57",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "7.2.11",
        "versionType": "semver",
        "lessThanOrEqual": "7.2.*"
      },
      {
        "status": "unaffected",
        "version": "7.3",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "drivers/net/amt.c",
      "include/net/amt.h"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-98968

Source reference: /cveMetadata/cveId

Publisher severity

high

Source reference: /containers/cna/metrics

Event
#55714 · Revision 1
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Publisher date
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