6.12-stable review patch. If anyone has any objections, please let me know.
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From: Ahmed S. Darwish darwi@linutronix.de
commit 1881148215c67151b146450fb89ec22fd92337a7 upstream.
CPUID leaf 0x2 emits one-byte descriptors in its four output registers EAX, EBX, ECX, and EDX. For these descriptors to be valid, the most significant bit (MSB) of each register must be clear.
Leaf 0x2 parsing at intel.c only validated the MSBs of EAX, EBX, and ECX, but left EDX unchecked.
Validate EDX's most-significant bit as well.
Fixes: e0ba94f14f74 ("x86/tlb_info: get last level TLB entry number of CPU") Signed-off-by: Ahmed S. Darwish darwi@linutronix.de Signed-off-by: Ingo Molnar mingo@kernel.org Cc: stable@kernel.org Cc: "H. Peter Anvin" hpa@zytor.com Cc: Linus Torvalds torvalds@linux-foundation.org Link: https://lore.kernel.org/r/20250304085152.51092-3-darwi@linutronix.de Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/kernel/cpu/intel.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/x86/kernel/cpu/intel.c +++ b/arch/x86/kernel/cpu/intel.c @@ -836,7 +836,7 @@ static void intel_detect_tlb(struct cpui cpuid(2, ®s[0], ®s[1], ®s[2], ®s[3]);
/* If bit 31 is set, this is an unknown format */ - for (j = 0 ; j < 3 ; j++) + for (j = 0 ; j < 4 ; j++) if (regs[j] & (1 << 31)) regs[j] = 0;