From mboxrd@z Thu Jan 1 00:00:00 1970 From: Cornelia Huck Date: Wed, 08 Feb 2023 16:03:22 +0100 Subject: [PATCH v2 4/6] KVM: arm64: Limit length in kvm_vm_ioctl_mte_copy_tags() to INT_MAX In-Reply-To: <20230208140105.655814-5-thuth@redhat.com> References: <20230208140105.655814-1-thuth@redhat.com> <20230208140105.655814-5-thuth@redhat.com> Message-ID: <87pmakmc79.fsf@redhat.com> List-Id: To: kvm-riscv@lists.infradead.org MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit On Wed, Feb 08 2023, Thomas Huth wrote: > In case of success, this function returns the amount of handled bytes. > However, this does not work for large values: The function is called > from kvm_arch_vm_ioctl() (which still returns a long), which in turn > is called from kvm_vm_ioctl() in virt/kvm/kvm_main.c. And that function > stores the return value in an "int r" variable. So the upper 32-bits > of the "long" return value are lost there. > > KVM ioctl functions should only return "int" values, so let's limit > the amount of bytes that can be requested here to INT_MAX to avoid > the problem with the truncated return value. We can then also change > the return type of the function to "int" to make it clearer that it > is not possible to return a "long" here. > > Fixes: f0376edb1ddc ("KVM: arm64: Add ioctl to fetch/store tags in a guest") > Signed-off-by: Thomas Huth > --- > Documentation/virt/kvm/api.rst | 3 ++- > arch/arm64/include/asm/kvm_host.h | 4 ++-- > arch/arm64/kvm/guest.c | 8 ++++++-- > 3 files changed, 10 insertions(+), 5 deletions(-) Reviewed-by: Cornelia Huck