[Bug 219104] New: A simple typo in kvm_main.c which will lead to erroneous memory access

[bugzilla-daemon@kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=219104

            Bug ID: 219104
           Summary: A simple typo in kvm_main.c which will lead to
                    erroneous memory access
           Product: Virtualization
           Version: unspecified
          Hardware: All
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P3
         Component: kvm
          Assignee: virtualization_kvm@kernel-bugs.osdl.org
          Reporter: zyr_ms@outlook.com
        Regression: No

It seems there is a rather simple typo in `virt/kvm/kvm_main.c` function
`kvm_clear_guest`.


// virt/kvm/kvm_main.c:#L3586
int kvm_clear_guest(struct kvm *kvm, gpa_t gpa, unsigned long len)
{
        const void *zero_page = (const void *)
__va(page_to_phys(ZERO_PAGE(0)));
        gfn_t gfn = gpa >> PAGE_SHIFT;
        int seg;
        int offset = offset_in_page(gpa);
        int ret;

        while ((seg = next_segment(len, offset)) != 0) {
                ret = kvm_write_guest_page(kvm, gfn, zero_page, offset, len);
                if (ret < 0)
                        return ret;
                offset = 0;
                len -= seg;
                ++gfn;
        }
        return 0;
}


The arg `len` of `kvm_write_guest_page(kvm, gfn, zero_page, offset, len)`
should be `seg`. And this error will lead to clearing a lot of incorrect
memory.

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