CVE-2026-74660

*** Pendiente de traducción *** In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> netfilter: ebt_nflog: pin the NFLOG backend<br /> <br /> nf_log_unregister() runs after the per-net teardown so its final RCU<br /> grace period also drains readers that obtained the logger from a per-net<br /> binding. However, ebt_nflog passes an explicit ULOG log type to<br /> nf_log_packet() without holding a reference on the selected logger module,<br /> unlike the xt_NFLOG and nft_log frontends.<br /> <br /> An ebtables nflog rule can therefore remain callable while nfnetlink_log<br /> is unloaded. The resulting interleaving is:<br /> <br /> CPU 0 CPU 1<br /> nfnetlink_log_fini()<br /> unregister_pernet_subsys()<br /> kfree(nfnl_log_pernet(net))<br /> ebt_nflog_tg()<br /> nf_log_packet()<br /> nfulnl_log_packet()<br /> instance_lookup_get_rcu()<br /> <br /> The global ULOG logger is still registered at this point, so CPU 1<br /> dereferences the per-net state after CPU 0 has freed it. KASAN reported:<br /> <br /> BUG: KASAN: slab-use-after-free in instance_lookup_get_rcu<br /> Read of size 8 at addr ff110001052e6210 by task poc/92<br /> Call Trace:<br /> instance_lookup_get_rcu+0x1ce/0x1f0 [nfnetlink_log]<br /> nfulnl_log_packet+0x248/0x2fb0 [nfnetlink_log]<br /> nf_log_packet+0x204/0x300<br /> ebt_nflog_tg+0x351/0x550<br /> ebt_do_table+0xedf/0x22b0<br /> Allocated by task 90:<br /> __kmalloc_noprof+0x186/0x470<br /> ops_init+0x6d/0x420<br /> register_pernet_operations+0x2f6/0x670<br /> register_pernet_subsys+0x23/0x40<br /> Freed by task 93:<br /> kfree+0x131/0x3c0<br /> ops_undo_list+0x3e3/0x700<br /> unregister_pernet_operations+0x232/0x490<br /> unregister_pernet_subsys+0x1c/0x30<br /> nfnetlink_log_fini+0x34/0x450 [nfnetlink_log]<br /> <br /> Acquire the ULOG logger module reference when an ebt_nflog rule is<br /> validated and release it when the rule is destroyed. Request the NFLOG<br /> backend for legacy callers when needed, matching xt_NFLOG. This prevents<br /> module teardown until all ebt_nflog rules have stopped using the logger.