CVE-2025-21959

In the Linux kernel, the following vulnerability has been resolved:

netfilter: nf_conncount: Fully initialize struct nf_conncount_tuple in insert_tree()

Since commit b36e4523d4d5 ("netfilter: nf_conncount: fix garbage collection confirm race"), cpu and jiffies32 were introduced to the struct nf_conncount_tuple.

The commit made nf_conncount_add() initialize conn->cpu and conn->jiffies32 when allocating the struct. In contrast, count_tree() was not changed to initialize them.

By commit 34848d5c896e ("netfilter: nf_conncount: Split insert and traversal"), count_tree() was split and the relevant allocation code now resides in insert_tree(). Initialize conn->cpu and conn->jiffies32 in insert_tree().

BUG: KMSAN: uninit-value in find_or_evict net/netfilter/nf_conncount.c:117 [inline] BUG: KMSAN: uninit-value in __nf_conncount_add+0xd9c/0x2850 net/netfilter/nf_conncount.c:143 find_or_evict net/netfilter/nf_conncount.c:117 [inline] __nf_conncount_add+0xd9c/0x2850 net/netfilter/nf_conncount.c:143 count_tree net/netfilter/nf_conncount.c:438 [inline] nf_conncount_count+0x82f/0x1e80 net/netfilter/nf_conncount.c:521 connlimit_mt+0x7f6/0xbd0 net/netfilter/xt_connlimit.c:72 __nft_match_eval net/netfilter/nft_compat.c:403 [inline] nft_match_eval+0x1a5/0x300 net/netfilter/nft_compat.c:433 expr_call_ops_eval net/netfilter/nf_tables_core.c:240 [inline] nft_do_chain+0x426/0x2290 net/netfilter/nf_tables_core.c:288 nft_do_chain_ipv4+0x1a5/0x230 net/netfilter/nft_chain_filter.c:23 nf_hook_entry_hookfn include/linux/netfilter.h:154 [inline] nf_hook_slow+0xf4/0x400 net/netfilter/core.c:626 nf_hook_slow_list+0x24d/0x860 net/netfilter/core.c:663 NF_HOOK_LIST include/linux/netfilter.h:350 [inline] ip_sublist_rcv+0x17b7/0x17f0 net/ipv4/ip_input.c:633 ip_list_rcv+0x9ef/0xa40 net/ipv4/ip_input.c:669 __netif_receive_skb_list_ptype net/core/dev.c:5936 [inline] __netif_receive_skb_list_core+0x15c5/0x1670 net/core/dev.c:5983 __netif_receive_skb_list...