CVE-2024-56643 dccp: Fix memory leak in dccp_feat_change_recv

Low 3.3 Published 27 Dec 2024 Updated 11 May 2026

A memory leak in the Linux kernel's DCCP implementation allows attackers to exhaust system memory, leading to denial of service.

Exploited in the wild: Not known
Login needed: Any signed-in user
Attackable: Local or same network only
Victim action needed: Not needed
Fix: Available

What is CVE-2024-56643?

CVE-2024-56643 is a low-severity denial of service vulnerability in Linux kernel, published on 27 Dec 2024. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

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

dccp: Fix memory leak in dccp_feat_change_recv

If dccp_feat_push_confirm() fails after new value for SP feature was accepted without reconciliation ('entry == NULL' branch), memory allocated for that value with dccp_feat_clone_sp_val() is never freed.

Here is the kmemleak stack for this:

unreferenced object 0xffff88801d4ab488 (size 8): comm "syz-executor310", pid 1127, jiffies 4295085598 (age 41.666s) hex dump (first 8 bytes): 01 b4 4a 1d 80 88 ff ff ..J..... backtrace: [<00000000db7cabfe>] kmemdup+0x23/0x50 mm/util.c:128 [<0000000019b38405>] kmemdup include/linux/string.h:465 [inline] [<0000000019b38405>] dccp_feat_clone_sp_val net/dccp/feat.c:371 [inline] [<0000000019b38405>] dccp_feat_clone_sp_val net/dccp/feat.c:367 [inline] [<0000000019b38405>] dccp_feat_change_recv net/dccp/feat.c:1145 [inline] [<0000000019b38405>] dccp_feat_parse_options+0x1196/0x2180 net/dccp/feat.c:1416 [<00000000b1f6d94a>] dccp_parse_options+0xa2a/0x1260 net/dccp/options.c:125 [<0000000030d7b621>] dccp_rcv_state_process+0x197/0x13d0 net/dccp/input.c:650 [<000000001f74c72e>] dccp_v4_do_rcv+0xf9/0x1a0 net/dccp/ipv4.c:688 [<00000000a6c24128>] sk_backlog_rcv include/net/sock.h:1041 [inline] [<00000000a6c24128>] __release_sock+0x139/0x3b0 net/core/sock.c:2570 [<00000000cf1f3a53>] release_sock+0x54/0x1b0 net/core/sock.c:3111 [<000000008422fa23>] inet_wait_for_connect net/ipv4/af_inet.c:603 [inline] [<000000008422fa23>] __inet_stream_connect+0x5d0/0xf70 net/ipv4/af_inet.c:696 [<0000000015b6f64d>] inet_stream_connect+0x53/0xa0 net/ipv4/af_inet.c:735 [<0000000010122488>] __sys_connect_file+0x15c/0x1a0 net/socket.c:1865 [<00000000b4b70023>] __sys_connect+0x165/0x1a0 net/socket.c:1882 [<00000000f4cb3815>] __do_sys_connect net/socket.c:1892 [inline] [<00000000f4cb3815>] __se_sys_connect net/socket.c:1889 [inline] [<00000000f4cb3815>] __x64_sys_connect+0x6e/0xb0 net/socket.c:1889 [<00000000e7b1e839>] do_syscall_64+0x33/0x40 arch/x86/entry/common.c:46 [<0000000055e91434>] entry_SYSCALL_64_after_hwframe+0x67/0xd1

Clean up the allocated memory in case of dccp_feat_push_confirm() failure and bail out with an error reset code.

Found by Linux Verification Center (linuxtesting.org) with Syzkaller.

Weakness: CWE-401

Which versions are affected by CVE-2024-56643?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2024-56643?

Apply the vendor's patch.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2024-56643 being exploited?

There is no known exploitation of CVE-2024-56643 in the wild and no public exploit code.

All Linux kernel vulnerabilities

Sources

Also known as AZL-54744, AZL-54917, BELL-CVE-2024-56643, DEBIAN-CVE-2024-56643, GHSA-g2f4-7x3w-9r2x, UBUNTU-CVE-2024-56643.