net: nexthop: fix percpu use-after-free in remove_nh_grp_entry
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- Fix
- Fixed in 6.12.78, 6.18.19, 6.19.9
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: none
- Automatable: no
- Technical impact: total
Summary
In the Linux kernel, the following vulnerability has been resolved: net: nexthop: fix percpu use-after-free in remove_nh_grp_entry When removing a nexthop from a group, remove_nh_grp_entry() publishes the new group via rcu_assign_pointer() then immediately frees the removed entry's percpu stats with free_percpu(). However, the synchronize_net() grace period in the caller remove_nexthop_from_groups() runs after the free. RCU readers that entered before the publish still see the old group and can dereference the freed stats via nh_grp_entry_stats_inc() -> get_cpu_ptr(nhge->stats), causing a use-after-free on percpu memory. Fix by deferring the free_percpu() until after synchronize_net() in the caller. Removed entries are chained via nh_list onto a local deferred free list. After the grace period completes and all RCU readers have finished, the percpu stats are safely freed.
Timeline
- CVE published
- CISA SSVC assessment
Exploitation: none · Automatable: no · Technical impact: total
- Record last updated
Affected versions
- Linux Linux
From f4676ea74b8549cd88dbfe2a592ce4530039e61f · fixed in abf4feaee6405f1441929c6ebe7a250f2cd170a7; From f4676ea74b8549cd88dbfe2a592ce4530039e61f · fixed in ab5ebab9664214ba41a7633cb4e72f128204f924; From f4676ea74b8549cd88dbfe2a592ce4530039e61f · fixed in 9e08ad731862b22a87cc55f752e16d66cdc9e231; From f4676ea74b8549cd88dbfe2a592ce4530039e61f · fixed in b2662e7593e94ae09b1cf7ee5f09160a3612bcb2
- Linux Linux
6.9
- KernelLinux
From 6.9.0 · fixed in 6.12.78; From 6.13.0 · fixed in 6.18.19; From 6.19.0 · fixed in 6.19.9