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Linux KernelOperating system · Linux

CVE-2024-56633

HIGH · 7.8 CVSS v3.1 Published 2024-12-27
Fix available
A fix is available. Upgrade to 5.4.287 / 5.10.231 or later.
See remediation →
80/100
Remediation priority · High
Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
In the Linux kernel, the following vulnerability has been resolved: tcp_bpf: Fix the sk_mem_uncharge logic in tcp_bpf_sendmsg The current sk memory accounting logic in __SK_REDIRECT is pre-uncharging tosend bytes, which is either msg->sg.size or a smaller value apply_bytes. Potential problems with this strategy are as follows: - If the actual sent bytes are smaller than tosend, we need to charge some bytes back, as in line 487, which is okay but seems not clean. - When tosend is set to apply_bytes, as in line 417, and (ret < 0), we may miss uncharging (msg->sg.size - apply_bytes) bytes. [...] 415 tosend = msg->sg.size; 416 if (psock->apply_bytes && psock->apply_bytes < tosend) 417 tosend = psock->apply_bytes; [...] 443 sk_msg_return(sk, msg, tosend); 444 release_sock(sk); 446 origsize = msg->sg.size; 447 ret = tcp_bpf_sendmsg_redir(sk_redir, redir_ingress, 448 msg, tosend, flags); 449 sent = origsize - msg->sg.size; [...] 454 lock_sock(sk); 455 if (unlikely(ret < 0)) { 456 int free = sk_msg_free_nocharge(sk, msg); 458 if (!cork) 459 *copied -= free; 460 } [...] 487 if (eval == __SK_REDIRECT) 488 sk_mem_charge(sk, tosend - sent); [...] When running the selftest test_txmsg_redir_wait_sndmem with txmsg_apply, the following warning will be reported: ------------[ cut here ]------------ WARNING: CPU: 6 PID: 57 at net/ipv4/af_inet.c:156 inet_sock_destruct+0x190/0x1a0 Modules linked in: CPU: 6 UID: 0 PID: 57 Comm: kworker/6:0 Not tainted 6.12.0-rc1.bm.1-amd64+ #43 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 Workqueue: events sk_psock_destroy RIP: 0010:inet_sock_destruct+0x190/0x1a0 RSP: 0018:ffffad0a8021fe08 EFLAGS: 00010206 RAX: 0000000000000011 RBX: ffff9aab4475b900 RCX: ffff9aab481a0800 RDX: 0000000000000303 RSI: 0000000000000011 RDI: ffff9aab4475b900 RBP: ffff9aab4475b990 R08: 0000000000000000 R09: ffff9aab40050ec0 R10: 0000000000000000 R11: ffff9aae6fdb1d01 R12: ffff9aab49c60400 R13: ffff9aab49c60598 R14: ffff9aab49c60598 R15: dead000000000100 FS: 0000000000000000(0000) GS:ffff9aae6fd80000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ffec7e47bd8 CR3: 00000001a1a1c004 CR4: 0000000000770ef0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 PKRU: 55555554 Call Trace: <TASK> ? __warn+0x89/0x130 ? inet_sock_destruct+0x190/0x1a0 ? report_bug+0xfc/0x1e0 ? handle_bug+0x5c/0xa0 ? exc_invalid_op+0x17/0x70 ? asm_exc_invalid_op+0x1a/0x20 ? inet_sock_destruct+0x190/0x1a0 __sk_destruct+0x25/0x220 sk_psock_destroy+0x2b2/0x310 process_scheduled_works+0xa3/0x3e0 worker_thread+0x117/0x240 ? __pfx_worker_thread+0x10/0x10 kthread+0xcf/0x100 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x31/0x40 ? __pfx_kthread+0x10/0x10 ret_from_fork_asm+0x1a/0x30 </TASK> ---[ end trace 0000000000000000 ]--- In __SK_REDIRECT, a more concise way is delaying the uncharging after sent bytes are finalized, and uncharge this value. When (ret < 0), we shall invoke sk_msg_free. Same thing happens in case __SK_DROP, when tosend is set to apply_bytes, we may miss uncharging (msg->sg.size - apply_bytes) bytes. The same warning will be reported in selftest. [...] 468 case __SK_DROP: 469 default: 470 sk_msg_free_partial(sk, msg, tosend); 471 sk_msg_apply_bytes(psock, tosend); 472 *copied -= (tosend + delta); 473 return -EACCES; [...] So instead of sk_msg_free_partial we can do sk_msg_free here.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis

A detailed technical summary for this CVE is being prepared.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Linux KernelOperating system
Affected:>= 4.20, < 5.4.287>= 5.5, < 5.10.231>= 5.11, < 5.15.174>= 5.16, < 6.1.120>= 6.2, < 6.6.66>= 6.7, < 6.12.5= 6.13

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 5.4.287 / 5.10.231 / 5.15.174 or later
Fixed in 5.4.2875.10.2315.15.174
Vendor patch git.kernel.org →
Recommended fix High confidence

Linux kernel >= 5.4.287 (5.4.x), >= 5.10.231 (5.10.x), >= 5.15.174 (5.15.x), or >= 6.1.120 (6.1.x)

  1. Identify the currently running Linux kernel version using `uname -r`
  2. Determine which version branch your kernel belongs to (e.g., 5.4.x, 5.10.x, 5.15.x, or 6.1.x)
  3. Upgrade the Linux kernel to a version that includes the fix: for 5.4.x series upgrade to >= 5.4.287, for 5.10.x series upgrade to >= 5.10.231, for 5.15.x series upgrade to >= 5.15.174, or for 6.1.x series upgrade to >= 6.1.120
  4. Apply the upgrade via your distribution's package manager (e.g., `apt-get dist-upgrade`, `yum update`, or `dnf upgrade`)
  5. Reboot the system to load the patched kernel
  6. Verify the fix by running the kernel version check and confirming the patch commit 0d6cd1151e26 is included
Caveat Kernel upgrades may require system reboot and could introduce compatibility issues with older drivers or modules; ensure backup and test in staging environment before production deployment

Generated from the published advisory — verify against the referenced sources before acting.

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $1,950. Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

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