6.12-stable review patch. If anyone has any objections, please let me know.
------------------
From: Björn Töpel <bjorn@xxxxxxxxxxxx>
[ Upstream commit 332fa4a802b16ccb727199da685294f85f9880cb ]
In kvm_riscv_vcpu_sbi_init() the entry->ext_idx can contain an
out-of-bound index. This is used as a special marker for the base
extensions, that cannot be disabled. However, when traversing the
extensions, that special marker is not checked prior indexing the
array.
Add an out-of-bounds check to the function.
Fixes: 56d8a385b605 ("RISC-V: KVM: Allow some SBI extensions to be disabled by default")
Signed-off-by: Björn Töpel <bjorn@xxxxxxxxxxxx>
Reviewed-by: Anup Patel <anup@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20241104191503.74725-1-bjorn@xxxxxxxxxx
Signed-off-by: Anup Patel <anup@xxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
arch/riscv/kvm/vcpu_sbi.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/arch/riscv/kvm/vcpu_sbi.c b/arch/riscv/kvm/vcpu_sbi.c
index 7de128be8db9b..6e704ed86a83a 100644
--- a/arch/riscv/kvm/vcpu_sbi.c
+++ b/arch/riscv/kvm/vcpu_sbi.c
@@ -486,19 +486,22 @@ void kvm_riscv_vcpu_sbi_init(struct kvm_vcpu *vcpu)
struct kvm_vcpu_sbi_context *scontext = &vcpu->arch.sbi_context;
const struct kvm_riscv_sbi_extension_entry *entry;
const struct kvm_vcpu_sbi_extension *ext;
- int i;
+ int idx, i;
for (i = 0; i < ARRAY_SIZE(sbi_ext); i++) {
entry = &sbi_ext[i];
ext = entry->ext_ptr;
+ idx = entry->ext_idx;
+
+ if (idx < 0 || idx >= ARRAY_SIZE(scontext->ext_status))
+ continue;
if (ext->probe && !ext->probe(vcpu)) {
- scontext->ext_status[entry->ext_idx] =
- KVM_RISCV_SBI_EXT_STATUS_UNAVAILABLE;
+ scontext->ext_status[idx] = KVM_RISCV_SBI_EXT_STATUS_UNAVAILABLE;
continue;
}
- scontext->ext_status[entry->ext_idx] = ext->default_disabled ?
+ scontext->ext_status[idx] = ext->default_disabled ?
KVM_RISCV_SBI_EXT_STATUS_DISABLED :
KVM_RISCV_SBI_EXT_STATUS_ENABLED;
}
--
2.43.0
