diff options
author | Gustavo A. R. Silva <gustavoars@kernel.org> | 2020-05-07 13:56:18 -0500 |
---|---|---|
committer | Paolo Bonzini <pbonzini@redhat.com> | 2020-06-01 04:26:05 -0400 |
commit | f4a9fdd5f12ad48700ad5dcb7a0dc7cf9a3bcd5a (patch) | |
tree | 416a924abbaa5fc88c608d3e2b25eacdaed31095 /arch | |
parent | a8387d0b471f7c8d4d936af0d6dc44dff5c41c6c (diff) |
KVM: VMX: Replace zero-length array with flexible-array
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:
struct foo {
int stuff;
struct boo array[];
};
By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.
Also, notice that, dynamic memory allocations won't be affected by
this change:
"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]
sizeof(flexible-array-member) triggers a warning because flexible array
members have incomplete type[1]. There are some instances of code in
which the sizeof operator is being incorrectly/erroneously applied to
zero-length arrays and the result is zero. Such instances may be hiding
some bugs. So, this work (flexible-array member conversions) will also
help to get completely rid of those sorts of issues.
This issue was found with the help of Coccinelle.
[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour")
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Message-Id: <20200507185618.GA14831@embeddedor>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch')
-rw-r--r-- | arch/x86/kvm/vmx/vmcs.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/kvm/vmx/vmcs.h b/arch/x86/kvm/vmx/vmcs.h index 481ad879197b..5c0ff80b85c0 100644 --- a/arch/x86/kvm/vmx/vmcs.h +++ b/arch/x86/kvm/vmx/vmcs.h @@ -19,7 +19,7 @@ struct vmcs_hdr { struct vmcs { struct vmcs_hdr hdr; u32 abort; - char data[0]; + char data[]; }; DECLARE_PER_CPU(struct vmcs *, current_vmcs); |