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CVE Record

CVE-2023-53133: bpf, sockmap: Fix an infinite loop error when len is 0 in tcp_bpf_recvmsg_parser()

In the Linux kernel, the following vulnerability has been resolved: bpf, sockmap: Fix an infinite loop error when len is 0 in tcp_bpf_recvmsg_parser() When the buffer length of the recvmsg system call is 0, we got the flollowing soft lockup problem: watchdog: BUG: soft lockup - CPU#3 stuck for 27s! [a.out:6149] CPU: 3 PID: 6149 Comm: a.out Kdump: loaded Not tainted 6.2.0+ #30 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.15.0-1 04/01/2014 RIP: 0010:remove_wait_queue+0xb/0xc0 Code: 5e 41 5f c3 cc cc cc cc 0f 1f 80 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 0f 1f 44 00 00 41 57 <41> 56 41 55 41 54 55 48 89 fd 53 48 89 f3 4c 8d 6b 18 4c 8d 73 20 RSP: 0018:ffff88811b5978b8 EFLAGS: 00000246 RAX: 0000000000000000 RBX: ffff88811a7d3780 RCX: ffffffffb7a4d768 RDX: dffffc0000000000 RSI: ffff88811b597908 RDI: ffff888115408040 RBP: 1ffff110236b2f1b R08: 0000000000000000 R09: ffff88811a7d37e7 R10: ffffed10234fa6fc R11: 0000000000000001 R12: ffff88811179b800 R13: 0000000000000001 R14: ffff88811a7d38a8 R15: ffff88811a7d37e0 FS: 00007f6fb5398740(0000) GS:ffff888237180000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000020000000 CR3: 000000010b6ba002 CR4: 0000000000370ee0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> tcp_msg_wait_data+0x279/0x2f0 tcp_bpf_recvmsg_parser+0x3c6/0x490 inet_recvmsg+0x280/0x290 sock_recvmsg+0xfc/0x120 ____sys_recvmsg+0x160/0x3d0 ___sys_recvmsg+0xf0/0x180 __sys_recvmsg+0xea/0x1a0 do_syscall_64+0x3f/0x90 entry_SYSCALL_64_after_hwframe+0x72/0xdc The logic in tcp_bpf_recvmsg_parser is as follows: msg_bytes_ready: copied = sk_msg_recvmsg(sk, psock, msg, len, flags); if (!copied) { wait data; goto msg_bytes_ready; } In this case, "copied" always is 0, the infinite loop occurs. According to the Linux system call man page, 0 should be returned in this case. Therefore, in tcp_bpf_recvmsg_parser(), if the length is 0, directly return. Also modify several other functions with the same problem.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

CVE-2023-53133 is a Linux kernel flaw where a zero-length recvmsg call on specific BPF sockmap TCP handling paths can trap the kernel in an infinite loop, causing a CPU soft lockup. The documented impact is availability disruption, not data theft or code execution.

Executive priority

Address through normal kernel patch governance, with higher priority for critical systems using eBPF networking or showing soft lockup symptoms. There is no sourced evidence of active exploitation or data compromise, but availability impact on production hosts can still be operationally serious.

Technical view

The bug is in tcp_bpf_recvmsg_parser() and similar functions. When len is 0, sk_msg_recvmsg() returns 0, then the parser waits and retries indefinitely instead of returning 0 as expected for zero-length recvmsg. Linux stable commits resolve this by returning directly when length is zero.

Likely exposure

Exposure is likely limited to Linux systems running affected kernel versions where BPF sockmap TCP receive paths are reachable. The source does not establish whether ordinary remote traffic alone can trigger it or what privileges are needed to set up the required path.

Exploitation context

The source bundle reports a reproducible soft lockup but provides no KEV listing, no public exploitation claim, and no CVSS. Treat active exploitation as unconfirmed. The most supported risk is local or workload-driven denial of service through CPU lockup.

Researcher notes

The source identifies a logic error around zero-length recvmsg handling in tcp_bpf_recvmsg_parser(). Evidence supports denial of service via infinite loop and soft lockup. Privilege requirements, remote reachability, and distribution-specific affected ranges are not established in the supplied bundle.

Mitigation direction

  • Check kernel vendor advisories for CVE-2023-53133 coverage.
  • Upgrade to a kernel containing the referenced stable fixes.
  • Prioritize systems using BPF sockmap or custom eBPF networking.
  • Apply normal change control for production kernel updates.
  • Monitor vendor backport status for maintained distribution kernels.

Validation and detection

  • Inventory Linux kernel versions across affected hosts.
  • Confirm whether BPF sockmap networking is used in workloads.
  • Map deployed kernels to the referenced stable fix commits.
  • Review system logs for soft lockup watchdog messages.
  • Verify distribution advisories before closing remediation tickets.
Prepared
Confidence
medium
Sources
7

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

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0CVSS vectors
3Timeline events
0ADP providers
6Source links

Vulnerability timeline

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  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

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Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux604326b41a6fb9b4a78b6179335decee0365cd8c, 604326b41a6fb9b4a78b6179335decee0365cd8c, 604326b41a6fb9b4a78b6179335decee0365cd8c, 604326b41a6fb9b4a78b6179335decee0365cd8c, 604326b41a6fb9b4a78b6179335decee0365cd8cunaffected
LinuxLinux4.20, 0, 5.10.258, 5.15.103, 6.1.20, 6.2.7, 6.3affected
Weakness

CWE details

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