Zero-length arrays are deprecated[1]. Replace struct kvm_nested_state's
"data" union 0-length arrays with flexible arrays. (How are the
sizes of these arrays verified?) Detected with GCC 13, using
-fstrict-flex-arrays=3:
arch/x86/kvm/svm/nested.c: In function 'svm_get_nested_state':
arch/x86/kvm/svm/nested.c:1536:17: error: array subscript 0 is outside array bounds of 'struct kvm_svm_nested_state_data[0]' [-Werror=array-bounds=]
1536 | &user_kvm_nested_state->data.svm[0];
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from include/uapi/linux/kvm.h:15,
from include/linux/kvm_host.h:40,
from arch/x86/kvm/svm/nested.c:18:
arch/x86/include/uapi/asm/kvm.h:511:50: note: while referencing 'svm'
511 | struct kvm_svm_nested_state_data svm[0];
| ^~~
[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-length-and-one-element-arrays
Cc: Sean Christopherson <seanjc@xxxxxxxxxx>
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: "Gustavo A. R. Silva" <gustavoars@xxxxxxxxxx>
Cc: x86@xxxxxxxxxx
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: kvm@xxxxxxxxxxxxxxx
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
arch/x86/include/uapi/asm/kvm.h | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h
index e48deab8901d..8ec3dfd641b0 100644
--- a/arch/x86/include/uapi/asm/kvm.h
+++ b/arch/x86/include/uapi/asm/kvm.h
@@ -502,13 +502,13 @@ struct kvm_nested_state {
} hdr;
/*
- * Define data region as 0 bytes to preserve backwards-compatability
+ * Define union of flexible arrays to preserve backwards-compatability
* to old definition of kvm_nested_state in order to avoid changing
* KVM_{GET,PUT}_NESTED_STATE ioctl values.
*/
union {
- struct kvm_vmx_nested_state_data vmx[0];
- struct kvm_svm_nested_state_data svm[0];
+ __DECLARE_FLEX_ARRAY(struct kvm_vmx_nested_state_data, vmx);
+ __DECLARE_FLEX_ARRAY(struct kvm_svm_nested_state_data, svm);
} data;
};
--
2.34.1
