CVE-2022-48912 — netfilter: fix use-after-free in __nf_register_net_hook()

Affected: Linux

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

netfilter: fix use-after-free in __nf_register_net_hook()

We must not dereference @new_hooks after nf_hook_mutex has been released, because other threads might have freed our allocated hooks already.

BUG: KASAN: use-after-free in nf_hook_entries_get_hook_ops include/linux/netfilter.h:130 [inline] BUG: KASAN: use-after-free in hooks_validate net/netfilter/core.c:171 [inline] BUG: KASAN: use-after-free in __nf_register_net_hook+0x77a/0x820 net/netfilter/core.c:438 Read of size 2 at addr ffff88801c1a8000 by task syz-executor237/4430

CPU: 1 PID: 4430 Comm: syz-executor237 Not tainted 5.17.0-rc5-syzkaller-00306-g2293be58d6a1 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: <TASK> __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/0x336 mm/kasan/report.c:255 __kasan_report mm/kasan/report.c:442 [inline] kasan_report.cold+0x83/0xdf mm/kasan/report.c:459 nf_hook_entries_get_hook_ops include/linux/netfilter.h:130 [inline] hooks_validate net/netfilter/core.c:171 [inline] __nf_register_net_hook+0x77a/0x820 net/netfilter/core.c:438 nf_register_net_hook+0x114/0x170 net/netfilter/core.c:571 nf_register_net_hooks+0x59/0xc0 net/netfilter/core.c:587 nf_synproxy_ipv6_init+0x85/0xe0 net/netfilter/nf_synproxy_core.c:1218 synproxy_tg6_check+0x30d/0x560 net/ipv6/netfilter/i…

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CVE-2022-48912 — netfilter: fix use-after-free in __nf_register_net_hook()