[PATCH 6.18 242/309] LoongArch: KVM: Handle the case that EIOINTCs coremap is empty

Greg Kroah-Hartman
2026-03-31T17:08:30Z

From: Huacai Chen <chenhuacai@loongson.cn>

commit b97bd69eb0f67b5f961b304d28e9ba45e202d841 upstream.

EIOINTC's coremap in eiointc_update_sw_coremap() can be empty, currently
we get a cpuid with -1 in this case, but we actually need 0 because it's
similar as the case that cpuid >= 4.

This fix an out-of-bounds access to kvm_arch::phyid_map::phys_map[].

Cc: <stable@vger.kernel.org>
Fixes: 3956a52bc05bd81 ("LoongArch: KVM: Add EIOINTC read and write functions")
Reported-by: Aurelien Jarno <aurel32@debian.org>
Link: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1131431
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/loongarch/kvm/intc/eiointc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/loongarch/kvm/intc/eiointc.c
+++ b/arch/loongarch/kvm/intc/eiointc.c
@@ -83,7 +83,7 @@ static inline void eiointc_update_sw_cor

if (!(s->status & BIT(EIOINTC_ENABLE_CPU_ENCODE))) {
cpuid = ffs(cpuid) - 1;
- cpuid = (cpuid >= 4) ? 0 : cpuid;
+ cpuid = ((cpuid < 0) || (cpuid >= 4)) ? 0 : cpuid;
}

vcpu = kvm_get_vcpu_by_cpuid(s->kvm, cpuid);