CVE-2026-23385

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

netfilter: nf_tables: clone set on flush only

Syzbot with fault injection triggered a failing memory allocation with GFP_KERNEL which results in a WARN splat:

iter.err WARNING: net/netfilter/nftablesapi.c:845 at nftmapdeactivate+0x34e/0x3c0 net/netfilter/nftablesapi.c:845, CPU#0: syz.0.17/5992 Modules linked in: CPU: 0 UID: 0 PID: 5992 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 RIP: 0010:nftmapdeactivate+0x34e/0x3c0 net/netfilter/nftablesapi.c:845 Code: 8b 05 86 5a 4e 09 48 3b 84 24 a0 00 00 00 75 62 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc cc e8 63 6d fa f7 90 <0f> 0b 90 43 +80 7c 35 00 00 0f 85 23 fe ff ff e9 26 fe ff ff 89 d9 RSP: 0018:ffffc900045af780 EFLAGS: 00010293 RAX: ffffffff89ca45bd RBX: 00000000fffffff4 RCX: ffff888028111e40 RDX: 0000000000000000 RSI: 00000000fffffff4 RDI: 0000000000000000 RBP: ffffc900045af870 R08: 0000000000400dc0 R09: 00000000ffffffff R10: dffffc0000000000 R11: fffffbfff1d141db R12: ffffc900045af7e0 R13: 1ffff920008b5f24 R14: dffffc0000000000 R15: ffffc900045af920 FS: 000055557a6a5500(0000) GS:ffff888125496000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fb5ea271fc0 CR3: 000000003269e000 CR4: 00000000003526f0 Call Trace: <TASK> __nftreleasetable+0xceb/0x11f0 net/netfilter/nftablesapi.c:12115 nftrcvnlevent+0xc25/0xdb0 net/netfilter/nftablesapi.c:12187 notifiercallchain+0x19d/0x3a0 kernel/notifier.c:85 blockingnotifiercallchain+0x6a/0x90 kernel/notifier.c:380 netlinkrelease+0x123b/0x1ad0 net/netlink/afnetlink.c:761 __sockrelease net/socket.c:662 [inline] sockclose+0xc3/0x240 net/socket.c:1455

Restrict set clone to the flush set command in the preparation phase. Add NFTITERUPDATE_CLONE and use it for this purpose, update the rbtree and pipapo backends to only clone the set when this iteration type is used.

As for the existing NFTITERUPDATE type, update the pipapo backend to use the existing set clone if available, otherwise use the existing set representation. After this update, there is no need to clone a set that is being deleted, this includes bound anonymous set.

An alternative approach to NFTITERUPDATE_CLONE is to add a .clone interface and call it from the flush set path.