From c67b103a8d553791701fc5ea37cf78f81f1f9a8f Mon Sep 17 00:00:00 2001 From: "Ahmed S. Darwish" Date: Tue, 4 Mar 2025 09:51:13 +0100 Subject: [PATCH] x86/cpu: Validate CPUID leaf 0x2 EDX output 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 Signed-off-by: Ingo Molnar Cc: stable@kernel.org Cc: "H. Peter Anvin" Cc: Linus Torvalds Link: https://lore.kernel.org/r/20250304085152.51092-3-darwi@linutronix.de Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/cpu/intel.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c index 0418606ec3c0..73f03074af15 100644 --- a/arch/x86/kernel/cpu/intel.c +++ b/arch/x86/kernel/cpu/intel.c @@ -959,7 +959,7 @@ static void intel_detect_tlb(struct cpuinfo_x86 *c) 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;