CVE-2024-42161

In the Linux kernel, the following vulnerability has been resolved:
bpf: Avoid uninitialized value in BPF_CORE_READ_BITFIELD
[Changes from V1:

• Use a default branch in the switch statement to initialize val'.] GCC warns that val’ may be used uninitialized in the
  BPF_CRE_READ_BITFIELD macro, defined in bpf_core_read.h as:
  […]
  unsigned long long val;
  […]
  switch (__CORE_RELO(s, field, BYTE_SIZE)) {
  case 1: val = *(const unsigned char *)p; break;
  case 2: val = *(const unsigned short *)p; break;
  case 4: val = *(const unsigned int *)p; break;
  case 8: val = *(const unsigned long long *)p; break;
  }
  […]
  val;
  }
  This patch adds a default entry in the switch statement that sets
  `val’ to zero in order to avoid the warning, and random values to be
  used in case __builtin_preserve_field_info returns unexpected values
  for BPF_FIELD_BYTE_SIZE.
  Tested in bpf-next master.
  No regressions.