Advisory Published
Updated

CVE-2024-53125: bpf: sync_linked_regs() must preserve subreg_def

First published: Wed Dec 04 2024(Updated: )

In the Linux kernel, the following vulnerability has been resolved: bpf: sync_linked_regs() must preserve subreg_def Range propagation must not affect subreg_def marks, otherwise the following example is rewritten by verifier incorrectly when BPF_F_TEST_RND_HI32 flag is set: 0: call bpf_ktime_get_ns call bpf_ktime_get_ns 1: r0 &= 0x7fffffff after verifier r0 &= 0x7fffffff 2: w1 = w0 rewrites w1 = w0 3: if w0 < 10 goto +0 --------------> r11 = 0x2f5674a6 (r) 4: r1 >>= 32 r11 <<= 32 (r) 5: r0 = r1 r1 |= r11 (r) 6: exit; if w0 < 0xa goto pc+0 r1 >>= 32 r0 = r1 exit (or zero extension of w1 at (2) is missing for architectures that require zero extension for upper register half). The following happens w/o this patch: - r0 is marked as not a subreg at (0); - w1 is marked as subreg at (2); - w1 subreg_def is overridden at (3) by copy_register_state(); - w1 is read at (5) but mark_insn_zext() does not mark (2) for zero extension, because w1 subreg_def is not set; - because of BPF_F_TEST_RND_HI32 flag verifier inserts random value for hi32 bits of (2) (marked (r)); - this random value is read at (5).

Credit: 416baaa9-dc9f-4396-8d5f-8c081fb06d67

Affected SoftwareAffected VersionHow to fix
Linux Kernel

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Frequently Asked Questions

  • What is the severity of CVE-2024-53125?

    CVE-2024-53125 has been classified with a high severity due to its potential impact on system stability and security in the Linux kernel.

  • How do I fix CVE-2024-53125?

    To fix CVE-2024-53125, update your Linux kernel to the latest patched version provided by your Linux distribution.

  • What versions of the Linux kernel are affected by CVE-2024-53125?

    CVE-2024-53125 affects multiple versions of the Linux kernel prior to the patch being released.

  • What are the potential impacts of CVE-2024-53125?

    The potential impacts of CVE-2024-53125 include incorrect behavior in BPF programs which can lead to system crashes or security vulnerabilities.

  • Who is responsible for addressing CVE-2024-53125?

    The responsibility for addressing CVE-2024-53125 lies with the maintainers of the Linux kernel and end-users who must apply the updates.

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