From 6213b701a9df047242e69672f56eba62ba0e2d8a Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Wed, 18 Jan 2023 11:59:09 -0800 Subject: [PATCH] KVM: x86: Replace 0-length arrays with flexible arrays 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 Cc: Paolo Bonzini Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: Dave Hansen Cc: "Gustavo A. R. Silva" Cc: x86@kernel.org Cc: "H. Peter Anvin" Cc: kvm@vger.kernel.org Signed-off-by: Kees Cook Reviewed-by: Sean Christopherson Link: https://lore.kernel.org/r/20230105190548.never.323-kees@kernel.org Link: https://lore.kernel.org/r/20230118195905.gonna.693-kees@kernel.org Signed-off-by: Sean Christopherson --- arch/x86/include/uapi/asm/kvm.h | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h index e48deab8901d..bde47f3a8c9d 100644 --- a/arch/x86/include/uapi/asm/kvm.h +++ b/arch/x86/include/uapi/asm/kvm.h @@ -9,6 +9,7 @@ #include #include +#include #define KVM_PIO_PAGE_OFFSET 1 #define KVM_COALESCED_MMIO_PAGE_OFFSET 2 @@ -507,8 +508,8 @@ struct kvm_nested_state { * 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; }; -- 2.11.0