ipip: fix skb leak in collect_md mode when metadata_dst allocation fails
In collect_md mode ipip_tunnel_rcv() returns 0 without freeing the skb
when ip_tun_rx_dst() fails to allocate the metadata_dst. ipip_rcv() and
mplsip_rcv() are registered as xfrm_tunnel handlers, so tunnel4_rcv()
and tunnelmpls4_rcv() read the zero return as "the packet has been
consumed" and do not free it either. The skb is leaked.
The other tunnel drivers all dispose of the packet at this point:
ip6_tunnel.c jumps to its drop label, ip_gre.c and ip6_gre.c return
PACKET_REJECT, which makes gre_rcv() free the skb. Only ipip returns 0.
Jump to the existing drop label instead. It frees the skb and still
returns 0, so the packet keeps being reported as consumed, which is what
we want here: the outer header has already been pulled, and neither the
remaining handlers nor an ICMP unreachable have any use for it.
Triggering this needs an ipip or mplsip tunnel in collect_md mode and an
atomic allocation failure, which is why it has gone unnoticed.
Analysis
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Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | |||||||||||||||||||||
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| Linux | Linux | unaffected |
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| Linux | Linux | affected |
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No data available yet.
No vendor fix or workaround currently provided.
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Tracking
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Sat, 12 Sep 2026 00:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Weaknesses | CWE-772 | |
| References |
| |
| Metrics |
threat_severity
|
cvssV3_1
|
Fri, 11 Sep 2026 23:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: ipip: fix skb leak in collect_md mode when metadata_dst allocation fails In collect_md mode ipip_tunnel_rcv() returns 0 without freeing the skb when ip_tun_rx_dst() fails to allocate the metadata_dst. ipip_rcv() and mplsip_rcv() are registered as xfrm_tunnel handlers, so tunnel4_rcv() and tunnelmpls4_rcv() read the zero return as "the packet has been consumed" and do not free it either. The skb is leaked. The other tunnel drivers all dispose of the packet at this point: ip6_tunnel.c jumps to its drop label, ip_gre.c and ip6_gre.c return PACKET_REJECT, which makes gre_rcv() free the skb. Only ipip returns 0. Jump to the existing drop label instead. It frees the skb and still returns 0, so the packet keeps being reported as consumed, which is what we want here: the outer header has already been pulled, and neither the remaining handlers nor an ICMP unreachable have any use for it. Triggering this needs an ipip or mplsip tunnel in collect_md mode and an atomic allocation failure, which is why it has gone unnoticed. | |
| Title | ipip: fix skb leak in collect_md mode when metadata_dst allocation fails | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-09-11T19:44:35.858Z
Reserved: 2026-09-11T19:38:34.725Z
Link: CVE-2026-89565
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-09-11T20:19:40.427
Modified: 2026-09-11T20:19:40.427
Link: CVE-2026-89565
Redhat
OpenCVE Enrichment
No data.