CVE-2024-50036: net: do not delay dst_entries_add() in dst_release()

Severity: high (CVSS 7.0 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-10-21 · updated 2026-08-04

Description

In the Linux kernel, the following vulnerability has been resolved: net: do not delay dst_entries_add() in dst_release() dst_entries_add() uses per-cpu data that might be freed at netns dismantle from ip6_route_net_exit() calling dst_entries_destroy() Before ip6_route_net_exit() can be called, we release all the dsts associated with this netns, via calls to dst_release(), which waits an rcu grace period before calling dst_destroy() dst_entries_add() use in dst_destroy() is racy, because dst_entries_destroy() could have been called already. Decrementing the number of dsts must happen sooner. Notes: 1) in CONFIG_XFRM case, dst_destroy() can call dst_release_immediate(child), this might also cause UAF if the child does not have DST_NOCOUNT set. IPSEC maintainers might take a look and see how to address this. 2) There is also discussion about removing this count of dst, which might happen in future kernels.

Affected products

Linux kernel: from 3.10.50 before 3.11; from 3.12.26 before 3.13; from 3.14.14 before 3.15; from 3.15.7 before 3.16; from 3.16 before 6.6.57; from 6.7 before 6.11.4 — fixed in 3.11, 3.13, 3.15, 3.16, 6.11.4, 6.6.57

How to fix

Upgrade to a fixed version: Linux kernel 3.11, 3.13, 3.15, 3.16. Check the vendor advisory for mitigations.

References

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