CVE-2023-54004 in Linux
Summary
by MITRE • 12/24/2025
In the Linux kernel, the following vulnerability has been resolved:
udplite: Fix NULL pointer dereference in __sk_mem_raise_allocated().
syzbot reported [0] a null-ptr-deref in sk_get_rmem0() while using
IPPROTO_UDPLITE (0x88):
14:25:52 executing program 1: r0 = socket$inet6(0xa, 0x80002, 0x88)
We had a similar report [1] for probably sk_memory_allocated_add()
in __sk_mem_raise_allocated(), and commit c915fe13cbaa ("udplite: fix NULL pointer dereference") fixed it by setting .memory_allocated for udplite_prot and udplitev6_prot.
To fix the variant, we need to set either .sysctl_wmem_offset or .sysctl_rmem.
Now UDP and UDPLITE share the same value for .memory_allocated, so we use the same .sysctl_wmem_offset for UDP and UDPLITE.
[0]:
general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 0 PID: 6829 Comm: syz-executor.1 Not tainted 6.4.0-rc2-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/28/2023 RIP: 0010:sk_get_rmem0 include/net/sock.h:2907 [inline]
RIP: 0010:__sk_mem_raise_allocated+0x806/0x17a0 net/core/sock.c:3006 Code: c1 ea 03 80 3c 02 00 0f 85 23 0f 00 00 48 8b 44 24 08 48 8b 98 38 01 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 da 48 c1 ea 03 <0f> b6 14 02 48 89 d8 83 e0 07 83 c0 03 38 d0 0f 8d 6f 0a 00 00 8b RSP: 0018:ffffc90005d7f450 EFLAGS: 00010246 RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffc90004d92000 RDX: 0000000000000000 RSI: ffffffff88066482 RDI: ffffffff8e2ccbb8 RBP: ffff8880173f7000 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000030000 R13: 0000000000000001 R14: 0000000000000340 R15: 0000000000000001 FS: 0000000000000000(0000) GS:ffff8880b9800000(0063) knlGS:00000000f7f1cb40 CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033 CR2: 000000002e82f000 CR3: 0000000034ff0000 CR4: 00000000003506f0 Call Trace: <TASK> __sk_mem_schedule+0x6c/0xe0 net/core/sock.c:3077 udp_rmem_schedule net/ipv4/udp.c:1539 [inline]
__udp_enqueue_schedule_skb+0x776/0xb30 net/ipv4/udp.c:1581 __udpv6_queue_rcv_skb net/ipv6/udp.c:666 [inline]
udpv6_queue_rcv_one_skb+0xc39/0x16c0 net/ipv6/udp.c:775 udpv6_queue_rcv_skb+0x194/0xa10 net/ipv6/udp.c:793 __udp6_lib_mcast_deliver net/ipv6/udp.c:906 [inline]
__udp6_lib_rcv+0x1bda/0x2bd0 net/ipv6/udp.c:1013 ip6_protocol_deliver_rcu+0x2e7/0x1250 net/ipv6/ip6_input.c:437 ip6_input_finish+0x150/0x2f0 net/ipv6/ip6_input.c:482 NF_HOOK include/linux/netfilter.h:303 [inline]
NF_HOOK include/linux/netfilter.h:297 [inline]
ip6_input+0xa0/0xd0 net/ipv6/ip6_input.c:491 ip6_mc_input+0x40b/0xf50 net/ipv6/ip6_input.c:585 dst_input include/net/dst.h:468 [inline]
ip6_rcv_finish net/ipv6/ip6_input.c:79 [inline]
NF_HOOK include/linux/netfilter.h:303 [inline]
NF_HOOK include/linux/netfilter.h:297 [inline]
ipv6_rcv+0x250/0x380 net/ipv6/ip6_input.c:309 __netif_receive_skb_one_core+0x114/0x180 net/core/dev.c:5491 __netif_receive_skb+0x1f/0x1c0 net/core/dev.c:5605 netif_receive_skb_internal net/core/dev.c:5691 [inline]
netif_receive_skb+0x133/0x7a0 net/core/dev.c:5750 tun_rx_batched+0x4b3/0x7a0 drivers/net/tun.c:1553 tun_get_user+0x2452/0x39c0 drivers/net/tun.c:1989 tun_chr_write_iter+0xdf/0x200 drivers/net/tun.c:2035 call_write_iter include/linux/fs.h:1868 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x945/0xd50 fs/read_write.c:584 ksys_write+0x12b/0x250 fs/read_write.c:637 do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline]
__do_fast_syscall_32+0x65/0xf0 arch/x86/entry/common.c:178 do_fast_syscall_32+0x33/0x70 arch/x86/entry/common.c:203 entry_SYSENTER_compat_after_hwframe+0x70/0x82 RIP: 0023:0xf7f21579 Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00 ---truncated---
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Analysis
by VulDB Data Team • 01/30/2026
The vulnerability identified as CVE-2023-54004 affects the Linux kernel and specifically targets the User Datagram Protocol Lite (UDPLITE) implementation. This flaw manifests as a NULL pointer dereference within the `__sk_mem_raise_allocated()` function, which is part of the socket memory management subsystem. The issue was initially reported by syzbot, an automated fuzzer, and manifests during operations involving IPPROTO_UDPLITE with a socket type of AF_INET6. The root cause lies in the improper initialization of socket memory tracking structures, particularly the missing setup of the `.memory_allocated` field for UDPLITE protocol handlers, leading to a kernel panic when attempting to access a null memory reference.
The technical flaw occurs in the context of socket memory allocation where the kernel attempts to manage memory usage for network sockets. When a UDPLITE socket is created and subsequently processes incoming packets, the system invokes functions like `sk_get_rmem0()` and `__sk_mem_raise_allocated()`. These functions rely on certain protocol-specific memory tracking fields being properly initialized. Without proper initialization of `.memory_allocated` for the UDPLITE protocol handlers (`udplite_prot` and `udplitev6_prot`), these functions encounter a null pointer dereference, resulting in a general protection fault. The vulnerability is classified under CWE-476 as a NULL pointer dereference, which is a common class of bugs leading to system instability and potential privilege escalation.
The operational impact of this vulnerability is significant as it can lead to kernel crashes and system instability when UDPLITE sockets are used in network operations. An attacker could potentially exploit this to cause a denial of service by triggering the NULL pointer dereference through crafted network packets. The vulnerability affects systems running Linux kernel versions where the fix has not been applied, particularly impacting systems that utilize UDPLITE protocol for communication. The issue is particularly concerning in environments where network reliability and stability are critical, as a single malicious packet could bring down the entire system or cause service disruption. According to ATT&CK framework, this vulnerability maps to T1499.004 (Endpoint Denial of Service) and potentially T1595.001 (Network Denial of Service) depending on how it's leveraged.
The fix for this vulnerability involves ensuring that the UDPLITE protocol handlers properly initialize their memory tracking structures, specifically setting the `.memory_allocated` field. The solution implemented in the kernel commit c915fe13cbaa addresses the issue by ensuring that both UDP and UDPLITE protocols share the same memory allocation tracking mechanisms, and by properly setting `.sysctl_wmem_offset` for UDPLITE. This approach aligns with the principle of maintaining consistent memory management across similar protocol implementations and prevents the NULL pointer dereference by ensuring all necessary fields are initialized before use. The fix also ensures that memory allocation tracking works consistently across both UDP and UDPLITE protocols, preventing similar issues from arising in other related functions that rely on the same memory management infrastructure.