Once an instruction crosses a page boundary, the size read from the second page
disregards the common case that part of the operand resides on the first page.
As a result, fetch of long insturctions may fail, and thereby cause the
decoding to fail as well.
Cc: stable@vger.kernel.org
Fixes: 5cfc7e0f5e5e1adf998df94f8e36edaf5d30d38e
Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
static __always_inline int do_insn_fetch_bytes(struct x86_emulate_ctxt *ctxt,
unsigned size)
{
- if (unlikely(ctxt->fetch.end - ctxt->fetch.ptr < size))
- return __do_insn_fetch_bytes(ctxt, size);
+ unsigned done_size = ctxt->fetch.end - ctxt->fetch.ptr;
+
+ if (unlikely(done_size < size))
+ return __do_insn_fetch_bytes(ctxt, size - done_size);
else
return X86EMUL_CONTINUE;
}