[86/98] KVM: S390: fix potential array overrun in intercept handling

[Greg KH]

2.6.32-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Christian Borntraeger <borntraeger@xxxxxxxxxx>

commit 062d5e9b0d714f449b261bb522eadaaf6f00f438 upstream.

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.

Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
Signed-off-by: Marcelo Tosatti <mtosatti@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 arch/s390/kvm/intercept.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/arch/s390/kvm/intercept.c
+++ b/arch/s390/kvm/intercept.c
@@ -213,7 +213,7 @@ static int handle_instruction_and_prog(s
 	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 @@ int kvm_handle_sie_intercept(struct kvm_
 	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)


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