KVM: S390: fix potential array overrun in intercept handling
kvm_handle_sie_intercept uses a jump table to get the intercept handler
for a SIE intercept. Static code analysis revealed a potential problem:
the intercept_funcs jump table was defined to contain (0x48 >> 2) entries,
but we only checked for code > 0x48 which would cause an off-by-one
array overflow if code == 0x48.
Use the compiler and ARRAY_SIZE to automatically set the limits.
Cc: stable@kernel.org
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
diff --git a/arch/s390/kvm/intercept.c b/arch/s390/kvm/intercept.c
index ba9d8a7..b400964 100644
--- a/arch/s390/kvm/intercept.c
+++ b/arch/s390/kvm/intercept.c
@@ -213,7 +213,7 @@
return rc2;
}
-static const intercept_handler_t intercept_funcs[0x48 >> 2] = {
+static const intercept_handler_t intercept_funcs[] = {
[0x00 >> 2] = handle_noop,
[0x04 >> 2] = handle_instruction,
[0x08 >> 2] = handle_prog,
@@ -230,7 +230,7 @@
intercept_handler_t func;
u8 code = vcpu->arch.sie_block->icptcode;
- if (code & 3 || code > 0x48)
+ if (code & 3 || (code >> 2) >= ARRAY_SIZE(intercept_funcs))
return -ENOTSUPP;
func = intercept_funcs[code >> 2];
if (func)