From: Nadav Amit <[email protected]> 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: [email protected] Fixes: 5cfc7e0f5e5e1adf998df94f8e36edaf5d30d38e Signed-off-by: Nadav Amit <[email protected]> Signed-off-by: Paolo Bonzini <[email protected]> --- arch/x86/kvm/emulate.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index c0deaff8d9f0..02c8ea804aaf 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -778,8 +778,10 @@ static int __do_insn_fetch_bytes(struct x86_emulate_ctxt *ctxt, int op_size) 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; } -- 1.8.3.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
