CVE-2024-49987 bpftool: Fix undefined behavior in qsort(NULL, 0, ...)

What is CVE-2024-49987?

CVE-2024-49987 is a medium-severity vulnerability in Linux kernel, published on 21 Oct 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:

bpftool: Fix undefined behavior in qsort(NULL, 0, ...)

When netfilter has no entry to display, qsort is called with qsort(NULL, 0, ...). This results in undefined behavior, as UBSan reports:

net.c:827:2: runtime error: null pointer passed as argument 1, which is declared to never be null

Although the C standard does not explicitly state whether calling qsort with a NULL pointer when the size is 0 constitutes undefined behavior, Section 7.1.4 of the C standard (Use of library functions) mentions:

"Each of the following statements applies unless explicitly stated otherwise in the detailed descriptions that follow: If an argument to a function has an invalid value (such as a value outside the domain of the function, or a pointer outside the address space of the program, or a null pointer, or a pointer to non-modifiable storage when the corresponding parameter is not const-qualified) or a type (after promotion) not expected by a function with variable number of arguments, the behavior is undefined."

To avoid this, add an early return when nf_link_info is NULL to prevent calling qsort with a NULL pointer.

Weakness: CWE-476

Which versions are affected by CVE-2024-49987?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2024-49987?

Apply the vendor's patch.

Is CVE-2024-49987 being exploited?

There is no known exploitation of CVE-2024-49987 in the wild and no public exploit code.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as AZL-51768, BELL-CVE-2024-49987, DEBIAN-CVE-2024-49987, GHSA-qf5q-fm5c-hc2p, ROOT-OS-DEBIAN-12-CVE-2024-49987, ROOT-OS-UBUNTU-2204-CVE-2024-49987 and 2 more.