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lguest: fix spurious BUG_ON() on invalid guest stack.
Impact: fix crash on misbehaving guest gpte_addr() contains a BUG_ON(), insisting that the present flag is set. We need to return before we call it if that isn't the case. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Cc: stable@kernel.org
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1 changed files with 3 additions and 1 deletions
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@ -373,8 +373,10 @@ unsigned long guest_pa(struct lg_cpu *cpu, unsigned long vaddr)
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/* First step: get the top-level Guest page table entry. */
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gpgd = lgread(cpu, gpgd_addr(cpu, vaddr), pgd_t);
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/* Toplevel not present? We can't map it in. */
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if (!(pgd_flags(gpgd) & _PAGE_PRESENT))
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if (!(pgd_flags(gpgd) & _PAGE_PRESENT)) {
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kill_guest(cpu, "Bad address %#lx", vaddr);
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return -1UL;
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}
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gpte = lgread(cpu, gpte_addr(gpgd, vaddr), pte_t);
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if (!(pte_flags(gpte) & _PAGE_PRESENT))
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