CVE-2024-49952

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

netfilter: nf_tables: prevent nf_skb_duplicated corruption

syzbot found that nf_dup_ipv4() or nf_dup_ipv6() could write

per-cpu variable nf_skb_duplicated in an unsafe way [1].

Disabling preemption as hinted by the splat is not enough,

we have to disable soft interrupts as well.

[1]

BUG: using __this_cpu_write() in preemptible [00000000] code: syz.4.282/6316

caller is nf_dup_ipv4+0x651/0x8f0 net/ipv4/netfilter/nf_dup_ipv4.c:87

CPU: 0 UID: 0 PID: 6316 Comm: syz.4.282 Not tainted 6.11.0-rc7-syzkaller-00104-g7052622fccb1 #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024

Call Trace:

<TASK>

__dump_stack lib/dump_stack.c:93 [inline]

dump_stack_lvl+0x241/0x360 lib/dump_stack.c:119

check_preemption_disabled+0x10e/0x120 lib/smp_processor_id.c:49

nf_dup_ipv4+0x651/0x8f0 net/ipv4/netfilter/nf_dup_ipv4.c:87

nft_dup_ipv4_eval+0x1db/0x300 net/ipv4/netfilter/nft_dup_ipv4.c:30

expr_call_ops_eval net/netfilter/nf_tables_core.c:240 [inline]

nft_do_chain+0x4ad/0x1da0 net/netfilter/nf_tables_core.c:288

nft_do_chain_ipv4+0x202/0x320 net/netfilter/nft_chain_filter.c:23

nf_hook_entry_hookfn include/linux/netfilter.h:154 [inline]

nf_hook_slow+0xc3/0x220 net/netfilter/core.c:626

nf_hook+0x2c4/0x450 include/linux/netfilter.h:269

NF_HOOK_COND include/linux/netfilter.h:302 [inline]

ip_output+0x185/0x230 net/ipv4/ip_output.c:433

ip_local_out net/ipv4/ip_output.c:129 [inline]

ip_send_skb+0x74/0x100 net/ipv4/ip_output.c:1495

udp_send_skb+0xacf/0x1650 net/ipv4/udp.c:981

udp_sendmsg+0x1c21/0x2a60 net/ipv4/udp.c:1269

sock_sendmsg_nosec net/socket.c:730 [inline]

__sock_sendmsg+0x1a6/0x270 net/socket.c:745

____sys_sendmsg+0x525/0x7d0 net/socket.c:2597

___sys_sendmsg net/socket.c:2651 [inline]

__sys_sendmmsg+0x3b2/0x740 net/socket.c:2737

__do_sys_sendmmsg net/socket.c:2766 [inline]

__se_sys_sendmmsg net/socket.c:2763 [inline]

__x64_sys_sendmmsg+0xa0/0xb0 net/socket.c:2763

do_syscall_x64 arch/x86/entry/common.c:52 [inline]

do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83

entry_SYSCALL_64_after_hwframe+0x77/0x7f

RIP: 0033:0x7f4ce4f7def9

Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48

RSP: 002b:00007f4ce5d4a038 EFLAGS: 00000246 ORIG_RAX: 0000000000000133

RAX: ffffffffffffffda RBX: 00007f4ce5135f80 RCX: 00007f4ce4f7def9

RDX: 0000000000000001 RSI: 0000000020005d40 RDI: 0000000000000006

RBP: 00007f4ce4ff0b76 R08: 0000000000000000 R09: 0000000000000000

R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000

R13: 0000000000000000 R14: 00007f4ce5135f80 R15: 00007ffd4cbc6d68

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