[Xen-changelog] [xen stable-4.12] x86/irq: Fix undefined behaviour in irq_move_cleanup_interrupt()

[patchbot@xxxxxxx]

commit 4c3eb3a6ba7aee71bbcd3adac8205650935a5b72
Author:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
AuthorDate: Fri Jul 5 10:21:27 2019 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri Jul 5 10:21:27 2019 +0200

    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@xxxxxxxxxx>
    Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
    Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
    master commit: 0bf4a2560dd24a7a1285727a900b52adcb4594fb
    master date: 2019-06-06 20:04:32 +0100
---
 xen/arch/x86/irq.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/xen/arch/x86/irq.c b/xen/arch/x86/irq.c
index 0035174d1f..f94602e45c 100644
--- 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());
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.12

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