UBUNTU-CVE-2026-72072: Use After Free
In the Linux kernel, the following vulnerability has been resolved: net/mlx5e: macsec: fix use-after-free of metadatadst on RX SC delete When an offloaded MACsec RX SC is deleted, macsecdelrxscctx() freed the per-SC metadatadst with metadatadstfree(), which kfree()s the object unconditionally and ignores the dst reference count. The RX datapath in mlx5emacsecoffloadhandlerxskb() looks up the SC under rcureadlock() via xaload(), takes a reference with dsthold() and attaches the dst to the skb with skbdstset(). A reader that already obtained the rxsc pointer can race with the delete path and operate on freed memory. Fix the owner side by dropping the reference with dstrelease() instead of freeing unconditionally, and convert the RX datapath to dstholdsafe() so a reader racing the SC delete cannot attach a dst whose last reference was just dropped; only attach it when a reference was actually taken. mlx5emacsecaddrxsc() also published scxarrayelement via xaalloc() before rxsc->mddst was allocated and initialised, so a datapath reader that looked the SC up by fsid could observe rxsc with mddst still NULL or, on weakly-ordered architectures, a non-NULL mddst pointer whose contents were not yet visible. NULL-check the xaload() result and mddst on the datapath, and reorder addrxsc() so the xaalloc() publish happens only after mddst is fully initialised; the xarray RCU publish then pairs with the rcureadlock()/xaload() in the datapath. Note: macsecdelrxscctx() also kfree()s rxsc->scxarrayelement without an RCU grace period while the same datapath reads it under rcureadlock(); that is a separate pre-existing issue left to a follow-up patch. Found by 0sec automated security-research tooling (https://0sec.ai).
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
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ubuntu/linuxto a version that resolves this vulnerability.Fixed in 6.8.0-147.147 - Upgrade
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ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 6.8.0-1067.70 - Upgrade
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ubuntu/linux-aws-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1014.14~24.04.1 - Upgrade
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ubuntu/linux-azureto a version that resolves this vulnerability.Fixed in 6.8.0-1071.79 - Upgrade
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ubuntu/linux-azure-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1017.17~24.04.1 - Upgrade
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ubuntu/linux-azure-fdeto a version that resolves this vulnerability.Fixed in 6.8.0-1069.76 - Upgrade
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ubuntu/linux-azure-fde-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1016.16~24.04.1 - Upgrade
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ubuntu/linux-gcpto a version that resolves this vulnerability.Fixed in 6.8.0-1071.79 - Upgrade
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ubuntu/linux-gcp-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1014.14~24.04.1 - Upgrade
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ubuntu/linux-gketo a version that resolves this vulnerability.Fixed in 6.8.0-1066.74 - Upgrade
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ubuntu/linux-gkeopto a version that resolves this vulnerability.Fixed in 6.8.0-1052.56 - Upgrade
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ubuntu/linux-hwe-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-38.38~24.04.4 - Upgrade
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ubuntu/linux-ibmto a version that resolves this vulnerability.Fixed in 6.8.0-1067.68 - Upgrade
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ubuntu/linux-lowlatencyto a version that resolves this vulnerability.Fixed in 6.8.0-147.147.1 - Upgrade
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ubuntu/linux-nvidia-tegrato a version that resolves this vulnerability.Fixed in 6.8.0-1036.39 - Upgrade
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ubuntu/linux-oracleto a version that resolves this vulnerability.Fixed in 6.8.0-1064.67 - Upgrade
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ubuntu/linux-oracle-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1013.13~24.04.1 - Upgrade
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ubuntu/linux-riscv-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-38.38.1~24.04.1 - Upgrade
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ubuntu/linux-bluefieldto a version that resolves this vulnerability.Fixed in 6.8.0-1033.38 - Upgrade
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ubuntu/linux-realtimeto a version that resolves this vulnerability.Fixed in 6.8.1-1062.63 - Upgrade
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ubuntu/linux-aws-fipsto a version that resolves this vulnerability.Fixed in 6.8.0-1067.70+fips1 - Upgrade
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ubuntu/linux-azure-fipsto a version that resolves this vulnerability.Fixed in 6.8.0-1071.79+fips1 - Upgrade
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ubuntu/linux-fipsto a version that resolves this vulnerability.Fixed in 6.8.0-147.147+fips1 - Upgrade
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ubuntu/linux-gcp-fipsto a version that resolves this vulnerability.Fixed in 6.8.0-1071.79+fips1 - Upgrade
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ubuntu/linuxto a version that resolves this vulnerability.Fixed in 7.0.0-38.38 - Upgrade
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ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 7.0.0-1014.14 - Upgrade
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ubuntu/linux-azureto a version that resolves this vulnerability.Fixed in 7.0.0-1017.17 - Upgrade
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ubuntu/linux-azure-fdeto a version that resolves this vulnerability.Fixed in 7.0.0-1016.16 - Upgrade
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ubuntu/linux-gcpto a version that resolves this vulnerability.Fixed in 7.0.0-1014.14 - Upgrade
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ubuntu/linux-gketo a version that resolves this vulnerability.Fixed in 7.0.0-1008.9 - Upgrade
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ubuntu/linux-ibmto a version that resolves this vulnerability.Fixed in 7.0.0-1015.15 - Upgrade
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ubuntu/linux-oem-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1015.15 - Upgrade
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ubuntu/linux-oracleto a version that resolves this vulnerability.Fixed in 7.0.0-1013.13 - Upgrade
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ubuntu/linux-realtimeto a version that resolves this vulnerability.Fixed in 7.0.0-38.38.1 - Upgrade
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ubuntu/linux-riscvto a version that resolves this vulnerability.Fixed in 7.0.0-38.38.1 - Compensating control
In the owner-side RX SC delete path, replace unconditional metadata_dst_free() with dst_release(); in the RX datapath, use dst_hold_safe() and attach the destination only when a reference was successfully taken.
- Compensating control
In mlx5e_macsec_add_rxsc(), fully allocate and initialize rx_sc->md_dst before publishing sc_xarray_element with xa_alloc(); in the RX datapath, NULL-check both xa_load() and md_dst before use.
Event History
Frequently Asked Questions
Which deployments are exposed to this issue?
Exposure requires use of the mlx5e MACsec offload receive path with offloaded MACsec RX secure channels. The affected packages listed are Ubuntu linux-riscv, linux-realtime, linux-azure, linux-gcp, linux-azure-fde, linux-gke, linux-hwe-edge, and linux-gkeop.
What condition triggers the vulnerable race?
The race occurs when an offloaded MACsec RX secure channel is deleted while an RX datapath reader has already looked up that channel or is attempting to take a reference to its metadata destination. This can result in the RX path operating on freed memory or attaching a destination whose final reference was dropped.
What does the fix change?
The fix releases the owner reference with dst_release() rather than unconditionally freeing the metadata destination. It also uses dst_hold_safe() in the RX path and ensures the metadata destination is allocated and initialized before the secure-channel entry is published.