CVE-2024-49987

Summary

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.

Affected Software

Weaknesses

ADP Enrichment

CISA ADP Vulnrichment

• SSVC:
• Exploitation: none
  • Automatable: no
  • Technical Impact: partial

References

• https://git.kernel.org/stable/c/c2d9f9a7837ab29ccae0c42252f17d436bf0a501
• https://git.kernel.org/stable/c/2e0f6f33f2aa87493b365a38a8fd87b8854b7734
• https://git.kernel.org/stable/c/c208b02827eb642758cef65641995fd3f38c89af
• https://git.kernel.org/stable/c/f04e2ad394e2755d0bb2d858ecb5598718bf00d5

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