2024-05-23 15:41:19

by Colin Ian King

Subject: [PATCH][next][V2] selftests: kvm: fix shift of 32 bit unsigned int more than 32 bits

Currrentl a 32 bit 1u value is being shifted more than 32 bits causing
overflow and incorrect checking of bits 32-63. Fix this by using the
BIT_ULL macro for shifting bits.

Detected by cppcheck:
sev_init2_tests.c:108:34: error: Shifting 32-bit value by 63 bits is
undefined behaviour [shiftTooManyBits]

Fixes: dfc083a181ba ("selftests: kvm: add tests for KVM_SEV_INIT2")
Signed-off-by: Colin Ian King <[email protected]>

---

V2: Fix incorrect variable in 2nd BIT_ULL(), kudos to Dan Carpenter for
catching this error.

---
tools/testing/selftests/kvm/x86_64/sev_init2_tests.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/kvm/x86_64/sev_init2_tests.c b/tools/testing/selftests/kvm/x86_64/sev_init2_tests.c
index 7a4a61be119b..ea09f7a06aa4 100644
--- a/tools/testing/selftests/kvm/x86_64/sev_init2_tests.c
+++ b/tools/testing/selftests/kvm/x86_64/sev_init2_tests.c
@@ -105,11 +105,11 @@ void test_features(uint32_t vm_type, uint64_t supported_features)
int i;

for (i = 0; i < 64; i++) {
- if (!(supported_features & (1u << i)))
+ if (!(supported_features & BIT_ULL(i)))
test_init2_invalid(vm_type,
&(struct kvm_sev_init){ .vmsa_features = BIT_ULL(i) },
"unknown feature");
- else if (KNOWN_FEATURES & (1u << i))
+ else if (KNOWN_FEATURES & BIT_ULL(i))
test_init2(vm_type,
&(struct kvm_sev_init){ .vmsa_features = BIT_ULL(i) });
}
--
2.39.2

2024-06-04 23:30:00

by Sean Christopherson

Subject: Re: [PATCH][next][V2] selftests: kvm: fix shift of 32 bit unsigned int more than 32 bits

On Thu, 23 May 2024 16:41:02 +0100, Colin Ian King wrote:
> Currrentl a 32 bit 1u value is being shifted more than 32 bits causing
> overflow and incorrect checking of bits 32-63. Fix this by using the
> BIT_ULL macro for shifting bits.
>
> Detected by cppcheck:
> sev_init2_tests.c:108:34: error: Shifting 32-bit value by 63 bits is
> undefined behaviour [shiftTooManyBits]
>
> [...]

Applied to kvm-x86 fixes, thanks!

[1/1] selftests: kvm: fix shift of 32 bit unsigned int more than 32 bits
https://github.com/kvm-x86/linux/commit/9a68cefe9f05

--
https://github.com/kvm-x86/linux/tree/next