In the Linux kernel, the following vulnerability has been resolved: x86/MCE/AMD: Use an u64 for bankmap Thee maximum number of MCA banks is 64 (MAXNRBANKS), see a0bc32b3cacf ("x86/mce: Increase maximum number of banks to 64"). However, the bankmap which contains a bitfield of which banks to initialize is of type unsigned int and that overflows when those bit numbers are >= 32, leading to UBSAN complaining correctly: UBSAN: shift-out-of-bounds in arch/x86/kernel/cpu/mce/amd.c:1365:38 shift exponent 32 is too large for 32-bit type 'int' Change the bankmap to a u64 and use the proper BITULL() macro when modifying bits in there. [ bp: Rewrite commit message. ]