x86/irq: Fix undefined behaviour in irq_move_cleanup_interrupt()

UBSAN reports:

  (XEN) ================================================================================
  (XEN) UBSAN: Undefined behaviour in irq.c:682:22
  (XEN) left shift of 1 by 31 places cannot be represented in type 'int'
  (XEN) ----[ Xen-4.13-unstable  x86_64  debug=y   Not tainted ]----
  (XEN) CPU:    16
  (XEN) RIP:    e008:[<ffff82d0802a54ce>] ubsan.c#ubsan_epilogue+0xa/0xc2
  <snip>
  (XEN) Xen call trace:
  (XEN)    [<ffff82d0802a54ce>] ubsan.c#ubsan_epilogue+0xa/0xc2
  (XEN)    [<ffff82d0802a6009>] __ubsan_handle_shift_out_of_bounds+0x15d/0x16c
  (XEN)    [<ffff82d08031ae77>] irq_move_cleanup_interrupt+0x25c/0x4a0
  (XEN)    [<ffff82d08031b585>] do_IRQ+0x19d/0x104c
  (XEN)    [<ffff82d08050c8ba>] common_interrupt+0x10a/0x120
  (XEN)    [<ffff82d0803b13a6>] cpu_idle.c#acpi_idle_do_entry+0x1de/0x24b
  (XEN)    [<ffff82d0803b1d83>] cpu_idle.c#acpi_processor_idle+0x5c8/0x94e
  (XEN)    [<ffff82d0802fa8d6>] domain.c#idle_loop+0xee/0x101
  (XEN)
  (XEN) ================================================================================

Switch to an unsigned shift, and correct the surrounding style.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
master commit: 0bf4a2560dd24a7a1285727a900b52adcb4594fb
master date: 2019-06-06 20:04:32 +0100

diff --git a/xen/arch/x86/irq.c b/xen/arch/x86/irq.c
index 0071b009bbfe9fd99a1b056f2e411bd5716959f7..3bb2f5132bfc5f20ce32b49ff240e2f21fdffa9a 100644 (file)
--- a/xen/arch/x86/irq.c
+++ b/xen/arch/x86/irq.c
@@ -679,7 +679,8 @@ void irq_move_cleanup_interrupt(struct cpu_user_regs *regs)
          * next attempt by sending another IRQ_MOVE_CLEANUP_VECTOR
          * to myself.
          */
-        if (irr  & (1 << (vector % 32))) {
+        if ( irr & (1u << (vector % 32)) )
+        {
             send_IPI_self(IRQ_MOVE_CLEANUP_VECTOR);
             TRACE_3D(TRC_HW_IRQ_MOVE_CLEANUP_DELAY,
                      irq, vector, smp_processor_id());