Messages in this thread Patch in this message | | | From | Kees Cook <> | Subject | [PATCH] KVM: x86: Replace 0-length arrays with flexible arrays | Date | Thu, 5 Jan 2023 11:05:49 -0800 |
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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@google.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org> Cc: x86@kernel.org Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: kvm@vger.kernel.org Signed-off-by: Kees Cook <keescook@chromium.org> --- 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
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