CVE-2023-53474

In the Linux kernel, the following vulnerability has been resolved:

x86/MCE/AMD: Use an u64 for bank_map

Thee maximum number of MCA banks is 64 (MAX_NR_BANKS), see

a0bc32b3cacf (x86/mce: Increase maximum number of banks to 64).

However, the bank_map 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 bank_map to a u64 and use the proper BIT_ULL() macro when modifying bits in there.

[ bp: Rewrite commit message. ]

Affected Software

References

• https://git.kernel.org/stable/c/11c58a0c1937c157dbdf82d5ab634d68c99f3098
• https://git.kernel.org/stable/c/4c1cdec319b9aadb65737c3eb1f5cb74bd6aa156
• https://git.kernel.org/stable/c/67bb7521b6420d81dab7538c0686f18f7d6d09f4
• https://git.kernel.org/stable/c/9669fa17287c3af2bbd4868d4c8fdd9e57f8332e
• https://git.kernel.org/stable/c/a9b9ea0e63a0ec5e97bf1219ab6dcbd55e362f83
• https://git.kernel.org/stable/c/ba8ffb1251eb629c2ec35220e3896cf4f7b888a7