Description

In the Linux kernel, the following vulnerability has been resolved: bpf: Check the helper function is valid in get_helper_proto kernel test robot reported verifier bug [1] where the helper func pointer could be NULL due to disabled config option. As Alexei suggested we could check on that in get_helper_proto directly. Marking tail_call helper func with BPF_PTR_POISON, because it is unused by design. [1] https://lore.kernel.org/oe-lkp/202507160818.68358831-lkp@intel.com

References 3

• git.kernel.org https://git.kernel.org/stable/c/3d429cb1278e995e22995ef117fa96d223a67e93
• git.kernel.org https://git.kernel.org/stable/c/6233715b4b714068d6c831d214a4e8792109875a
• git.kernel.org https://git.kernel.org/stable/c/e4414b01c1cd9887bbde92f946c1ba94e40d6d64

Remediation