Currently if io port + len crosses 8bit boundary in io permission bitmap the check may allow IO that otherwise should not be allowed. The patch fixes that.
Signed-off-by: Gleb Natapov <[email protected]> --- arch/x86/kvm/emulate.c | 5 ++--- 1 files changed, 2 insertions(+), 3 deletions(-) diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index b54b586..14c5ad5 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -1769,8 +1769,7 @@ static bool emulator_io_port_access_allowed(struct x86_emulate_ctxt *ctxt, struct desc_struct tr_seg; u32 base3; int r; - u16 io_bitmap_ptr; - u8 perm, bit_idx = port & 0x7; + u16 io_bitmap_ptr, perm, bit_idx = port & 0x7; unsigned mask = (1 << len) - 1; unsigned long base; @@ -1788,7 +1787,7 @@ static bool emulator_io_port_access_allowed(struct x86_emulate_ctxt *ctxt, return false; if (io_bitmap_ptr + port/8 > desc_limit_scaled(&tr_seg)) return false; - r = ops->read_std(base + io_bitmap_ptr + port/8, &perm, 1, ctxt->vcpu, + r = ops->read_std(base + io_bitmap_ptr + port/8, &perm, 2, ctxt->vcpu, NULL); if (r != X86EMUL_CONTINUE) return false; -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
