CVE-2021-47106 — netfilter: nf_tables: fix use-after-free in nft_set_catchall_destroy()

2026-10-07T20:49:06.792432+00:00

Affected: Linux

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

netfilter: nf_tables: fix use-after-free in nft_set_catchall_destroy()

We need to use list_for_each_entry_safe() iterator because we can not access @catchall after kfree_rcu() call.

syzbot reported:

BUG: KASAN: use-after-free in nft_set_catchall_destroy net/netfilter/nf_tables_api.c:4486 [inline] BUG: KASAN: use-after-free in nft_set_destroy net/netfilter/nf_tables_api.c:4504 [inline] BUG: KASAN: use-after-free in nft_set_destroy+0x3fd/0x4f0 net/netfilter/nf_tables_api.c:4493 Read of size 8 at addr ffff8880716e5b80 by task syz-executor.3/8871

CPU: 1 PID: 8871 Comm: syz-executor.3 Not tainted 5.16.0-rc5-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 print_address_description.constprop.0.cold+0x8d/0x2ed mm/kasan/report.c:247 __kasan_report mm/kasan/report.c:433 [inline] kasan_report.cold+0x83/0xdf mm/kasan/report.c:450 nft_set_catchall_destroy net/netfilter/nf_tables_api.c:4486 [inline] nft_set_destroy net/netfilter/nf_tables_api.c:4504 [inline] nft_set_destroy+0x3fd/0x4f0 net/netfilter/nf_tables_api.c:4493 __nft_release_table+0x79f/0xcd0 net/netfilter/nf_tables_api.c:9626 nft_rcv_nl_event+0x4f8/0x670 net/netfilter/nf_tables_api.c:9688 notifier_call_chain+0xb5/0x200 kernel/notifier.c:83 blocking_notifier_call_chain kernel/notifier.…

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CVE-2021-47106 — netfilter: nf_tables: fix use-after-free in nft_set_catchall_destroy()