CVE-2023-53343
Fecha de publicación:
17/09/2025
*** Pendiente de traducción *** In the Linux kernel, the following vulnerability has been resolved:<br />
<br />
icmp6: Fix null-ptr-deref of ip6_null_entry->rt6i_idev in icmp6_dev().<br />
<br />
With some IPv6 Ext Hdr (RPL, SRv6, etc.), we can send a packet that<br />
has the link-local address as src and dst IP and will be forwarded to<br />
an external IP in the IPv6 Ext Hdr.<br />
<br />
For example, the script below generates a packet whose src IP is the<br />
link-local address and dst is updated to 11::.<br />
<br />
# for f in $(find /proc/sys/net/ -name *seg6_enabled*); do echo 1 > $f; done<br />
# python3<br />
>>> from socket import *<br />
>>> from scapy.all import *<br />
>>><br />
>>> SRC_ADDR = DST_ADDR = "fe80::5054:ff:fe12:3456"<br />
>>><br />
>>> pkt = IPv6(src=SRC_ADDR, dst=DST_ADDR)<br />
>>> pkt /= IPv6ExtHdrSegmentRouting(type=4, addresses=["11::", "22::"], segleft=1)<br />
>>><br />
>>> sk = socket(AF_INET6, SOCK_RAW, IPPROTO_RAW)<br />
>>> sk.sendto(bytes(pkt), (DST_ADDR, 0))<br />
<br />
For such a packet, we call ip6_route_input() to look up a route for the<br />
next destination in these three functions depending on the header type.<br />
<br />
* ipv6_rthdr_rcv()<br />
* ipv6_rpl_srh_rcv()<br />
* ipv6_srh_rcv()<br />
<br />
If no route is found, ip6_null_entry is set to skb, and the following<br />
dst_input(skb) calls ip6_pkt_drop().<br />
<br />
Finally, in icmp6_dev(), we dereference skb_rt6_info(skb)->rt6i_idev->dev<br />
as the input device is the loopback interface. Then, we have to check if<br />
skb_rt6_info(skb)->rt6i_idev is NULL or not to avoid NULL pointer deref<br />
for ip6_null_entry.<br />
<br />
BUG: kernel NULL pointer dereference, address: 0000000000000000<br />
PF: supervisor read access in kernel mode<br />
PF: error_code(0x0000) - not-present page<br />
PGD 0 P4D 0<br />
Oops: 0000 [#1] PREEMPT SMP PTI<br />
CPU: 0 PID: 157 Comm: python3 Not tainted 6.4.0-11996-gb121d614371c #35<br />
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014<br />
RIP: 0010:icmp6_send (net/ipv6/icmp.c:436 net/ipv6/icmp.c:503)<br />
Code: fe ff ff 48 c7 40 30 c0 86 5d 83 e8 c6 44 1c 00 e9 c8 fc ff ff 49 8b 46 58 48 83 e0 fe 0f 84 4a fb ff ff 48 8b 80 d0 00 00 00 8b 00 44 8b 88 e0 00 00 00 e9 34 fb ff ff 4d 85 ed 0f 85 69 01<br />
RSP: 0018:ffffc90000003c70 EFLAGS: 00000286<br />
RAX: 0000000000000000 RBX: 0000000000000001 RCX: 00000000000000e0<br />
RDX: 0000000000000021 RSI: 0000000000000000 RDI: ffff888006d72a18<br />
RBP: ffffc90000003d80 R08: 0000000000000000 R09: 0000000000000001<br />
R10: ffffc90000003d98 R11: 0000000000000040 R12: ffff888006d72a10<br />
R13: 0000000000000000 R14: ffff8880057fb800 R15: ffffffff835d86c0<br />
FS: 00007f9dc72ee740(0000) GS:ffff88807dc00000(0000) knlGS:0000000000000000<br />
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033<br />
CR2: 0000000000000000 CR3: 00000000057b2000 CR4: 00000000007506f0<br />
PKRU: 55555554<br />
Call Trace:<br />
<br />
ip6_pkt_drop (net/ipv6/route.c:4513)<br />
ipv6_rthdr_rcv (net/ipv6/exthdrs.c:640 net/ipv6/exthdrs.c:686)<br />
ip6_protocol_deliver_rcu (net/ipv6/ip6_input.c:437 (discriminator 5))<br />
ip6_input_finish (./include/linux/rcupdate.h:781 net/ipv6/ip6_input.c:483)<br />
__netif_receive_skb_one_core (net/core/dev.c:5455)<br />
process_backlog (./include/linux/rcupdate.h:781 net/core/dev.c:5895)<br />
__napi_poll (net/core/dev.c:6460)<br />
net_rx_action (net/core/dev.c:6529 net/core/dev.c:6660)<br />
__do_softirq (./arch/x86/include/asm/jump_label.h:27 ./include/linux/jump_label.h:207 ./include/trace/events/irq.h:142 kernel/softirq.c:554)<br />
do_softirq (kernel/softirq.c:454 kernel/softirq.c:441)<br />
<br />
<br />
__local_bh_enable_ip (kernel/softirq.c:381)<br />
__dev_queue_xmit (net/core/dev.c:4231)<br />
ip6_finish_output2 (./include/net/neighbour.h:544 net/ipv6/ip6_output.c:135)<br />
rawv6_sendmsg (./include/net/dst.h:458 ./include/linux/netfilter.h:303 net/ipv6/raw.c:656 net/ipv6/raw.c:914)<br />
sock_sendmsg (net/socket.c:725 net/socket.c:748)<br />
__sys_sendto (net/socket.c:2134)<br />
__x64_sys_sendto (net/socket.c:2146 net/socket.c:2142 net/socket.c:2142)<br />
do_syscall_64 (arch/x86/entry/common.c:50 arch/x86/entry/common.c:80)<br />
entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:120)<br />
RIP: 0033:0x7f9dc751baea<br />
Code: d8 64 89 02 48 c7 c0 ff f<br />
---truncated---
Gravedad: Pendiente de análisis
Última modificación:
17/09/2025