Cmnt: [SRU][F][PATCH 1/1] netfilter: nf_reject_ipv6: fix potential crash in nf_send_reset6()
Koichiro Den
koichiro.den at canonical.com
Wed Mar 5 03:43:45 UTC 2025
On Mon, Mar 03, 2025 at 01:18:28PM GMT, Andrei Gherzan wrote:
> From: Eric Dumazet <edumazet at google.com>
>
> I got a syzbot report without a repro [1] crashing in nf_send_reset6()
>
> I think the issue is that dev->hard_header_len is zero, and we attempt
> later to push an Ethernet header.
>
> Use LL_MAX_HEADER, as other functions in net/ipv6/netfilter/nf_reject_ipv6.c.
>
> [1]
>
> skbuff: skb_under_panic: text:ffffffff89b1d008 len:74 put:14 head:ffff88803123aa00 data:ffff88803123a9f2 tail:0x3c end:0x140 dev:syz_tun
> kernel BUG at net/core/skbuff.c:206 !
> Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI
> CPU: 0 UID: 0 PID: 7373 Comm: syz.1.568 Not tainted 6.12.0-rc2-syzkaller-00631-g6d858708d465 #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
> RIP: 0010:skb_panic net/core/skbuff.c:206 [inline]
> RIP: 0010:skb_under_panic+0x14b/0x150 net/core/skbuff.c:216
> Code: 0d 8d 48 c7 c6 60 a6 29 8e 48 8b 54 24 08 8b 0c 24 44 8b 44 24 04 4d 89 e9 50 41 54 41 57 41 56 e8 ba 30 38 02 48 83 c4 20 90 <0f> 0b 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3
> RSP: 0018:ffffc900045269b0 EFLAGS: 00010282
> RAX: 0000000000000088 RBX: dffffc0000000000 RCX: cd66dacdc5d8e800
> RDX: 0000000000000000 RSI: 0000000000000200 RDI: 0000000000000000
> RBP: ffff88802d39a3d0 R08: ffffffff8174afec R09: 1ffff920008a4ccc
> R10: dffffc0000000000 R11: fffff520008a4ccd R12: 0000000000000140
> R13: ffff88803123aa00 R14: ffff88803123a9f2 R15: 000000000000003c
> FS: 00007fdbee5ff6c0(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000000000000 CR3: 000000005d322000 CR4: 00000000003526f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
> <TASK>
> skb_push+0xe5/0x100 net/core/skbuff.c:2636
> eth_header+0x38/0x1f0 net/ethernet/eth.c:83
> dev_hard_header include/linux/netdevice.h:3208 [inline]
> nf_send_reset6+0xce6/0x1270 net/ipv6/netfilter/nf_reject_ipv6.c:358
> nft_reject_inet_eval+0x3b9/0x690 net/netfilter/nft_reject_inet.c:48
> 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_inet+0x418/0x6b0 net/netfilter/nft_chain_filter.c:161
> nf_hook_entry_hookfn include/linux/netfilter.h:154 [inline]
> nf_hook_slow+0xc3/0x220 net/netfilter/core.c:626
> nf_hook include/linux/netfilter.h:269 [inline]
> NF_HOOK include/linux/netfilter.h:312 [inline]
> br_nf_pre_routing_ipv6+0x63e/0x770 net/bridge/br_netfilter_ipv6.c:184
> nf_hook_entry_hookfn include/linux/netfilter.h:154 [inline]
> nf_hook_bridge_pre net/bridge/br_input.c:277 [inline]
> br_handle_frame+0x9fd/0x1530 net/bridge/br_input.c:424
> __netif_receive_skb_core+0x13e8/0x4570 net/core/dev.c:5562
> __netif_receive_skb_one_core net/core/dev.c:5666 [inline]
> __netif_receive_skb+0x12f/0x650 net/core/dev.c:5781
> netif_receive_skb_internal net/core/dev.c:5867 [inline]
> netif_receive_skb+0x1e8/0x890 net/core/dev.c:5926
> tun_rx_batched+0x1b7/0x8f0 drivers/net/tun.c:1550
> tun_get_user+0x3056/0x47e0 drivers/net/tun.c:2007
> tun_chr_write_iter+0x10d/0x1f0 drivers/net/tun.c:2053
> new_sync_write fs/read_write.c:590 [inline]
> vfs_write+0xa6d/0xc90 fs/read_write.c:683
> ksys_write+0x183/0x2b0 fs/read_write.c:736
> 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: 0033:0x7fdbeeb7d1ff
> Code: 89 54 24 18 48 89 74 24 10 89 7c 24 08 e8 c9 8d 02 00 48 8b 54 24 18 48 8b 74 24 10 41 89 c0 8b 7c 24 08 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 31 44 89 c7 48 89 44 24 08 e8 1c 8e 02 00 48
> RSP: 002b:00007fdbee5ff000 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
> RAX: ffffffffffffffda RBX: 00007fdbeed36058 RCX: 00007fdbeeb7d1ff
> RDX: 000000000000008e RSI: 0000000020000040 RDI: 00000000000000c8
> RBP: 00007fdbeebf12be R08: 0000000000000000 R09: 0000000000000000
> R10: 000000000000008e R11: 0000000000000293 R12: 0000000000000000
> R13: 0000000000000000 R14: 00007fdbeed36058 R15: 00007ffc38de06e8
> </TASK>
>
> Fixes: c8d7b98bec43 ("netfilter: move nf_send_resetX() code to nf_reject_ipvX modules")
> Reported-by: syzbot <syzkaller at googlegroups.com>
> Signed-off-by: Eric Dumazet <edumazet at google.com>
> Signed-off-by: Pablo Neira Ayuso <pablo at netfilter.org>
> (backported from commit 4ed234fe793f27a3b151c43d2106df2ff0d81aac)
> [agherzan: `br_indev` context failed because it was removed as part of
> `physindev` to `physinif` work. The patch was adapted to keep that in
> place. The same was done for the return value of
> `nf_reject_ip6hdr_put`, which was dropped during the warning fix in
> a542f484594d2b7ebc189602418ac695e70b6fe1.]
nit: this is jammy-specific commit id.
> CVE-2024-50256
> Signed-off-by: Andrei Gherzan <andrei.gherzan at canonical.com>
> ---
> net/ipv6/netfilter/nf_reject_ipv6.c | 15 +++++++--------
> 1 file changed, 7 insertions(+), 8 deletions(-)
>
> diff --git a/net/ipv6/netfilter/nf_reject_ipv6.c b/net/ipv6/netfilter/nf_reject_ipv6.c
> index 4fdd587e08742..82b048651e82f 100644
> --- a/net/ipv6/netfilter/nf_reject_ipv6.c
> +++ b/net/ipv6/netfilter/nf_reject_ipv6.c
> @@ -119,13 +119,13 @@ EXPORT_SYMBOL_GPL(nf_reject_ip6_tcphdr_put);
> void nf_send_reset6(struct net *net, struct sk_buff *oldskb, int hook)
> {
> struct net_device *br_indev __maybe_unused;
> - struct sk_buff *nskb;
> - struct tcphdr _otcph;
> - const struct tcphdr *otcph;
> - unsigned int otcplen, hh_len;
> const struct ipv6hdr *oip6h = ipv6_hdr(oldskb);
> struct ipv6hdr *ip6h;
> struct dst_entry *dst = NULL;
> + const struct tcphdr *otcph;
> + struct sk_buff *nskb;
> + struct tcphdr _otcph;
> + unsigned int otcplen;
> struct flowi6 fl6;
>
> if ((!(ipv6_addr_type(&oip6h->saddr) & IPV6_ADDR_UNICAST)) ||
> @@ -156,9 +156,8 @@ void nf_send_reset6(struct net *net, struct sk_buff *oldskb, int hook)
> if (IS_ERR(dst))
> return;
>
> - hh_len = (dst->dev->hard_header_len + 15)&~15;
> - nskb = alloc_skb(hh_len + 15 + dst->header_len + sizeof(struct ipv6hdr)
> - + sizeof(struct tcphdr) + dst->trailer_len,
> + nskb = alloc_skb(LL_MAX_HEADER + sizeof(struct ipv6hdr) +
> + sizeof(struct tcphdr) + dst->trailer_len,
> GFP_ATOMIC);
>
> if (!nskb) {
> @@ -171,7 +170,7 @@ void nf_send_reset6(struct net *net, struct sk_buff *oldskb, int hook)
>
> nskb->mark = fl6.flowi6_mark;
>
> - skb_reserve(nskb, hh_len + dst->header_len);
> + skb_reserve(nskb, LL_MAX_HEADER);
> ip6h = nf_reject_ip6hdr_put(nskb, oldskb, IPPROTO_TCP,
> ip6_dst_hoplimit(dst));
> nf_reject_ip6_tcphdr_put(nskb, oldskb, otcph, otcplen);
> --
> 2.43.0
>
>
> --
> kernel-team mailing list
> kernel-team at lists.ubuntu.com
> https://lists.ubuntu.com/mailman/listinfo/kernel-team
More information about the kernel-team
mailing list