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

Vulnerability summary

CVE-2024-49987 is a medium (CVSS 5.5) NULL Pointer Dereference vulnerability in linux. EPSS estimates a 0.24% chance of exploitation in the next 30 days, higher than 14.4% of scored vulnerabilities.

Timeline

1. 21-10-2024
   PublishedVulnerability first disclosed.
2. 11-05-2026
   Last modifiedVulnerability information updated.

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.

• CWE-476NULL Pointer DereferenceThe product dereferences a pointer that it expects to be valid but is NULL.