CVE-2024-50036

/// Technical 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.

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References