[Xen-changelog] [xen master] xen/arm: Don't emulate the MMIO access if the instruction syndrome is invalid

[patchbot@xxxxxxx]

commit d2a167258b0b10567eb7abe3f34cf14660ed424e
Author:     Julien Grall <julien.grall@xxxxxxxxxx>
AuthorDate: Thu Jul 25 16:21:30 2013 +0100
Commit:     Ian Campbell <ian.campbell@xxxxxxxxxx>
CommitDate: Mon Jul 29 16:54:48 2013 +0100

    xen/arm: Don't emulate the MMIO access if the instruction syndrome is 
invalid
    
    When the instruction syndrome is not valid, the transfer register is 
unknown.
    If this register is used in the emulation code (it's the case for the VGIC),
    Xen can retrieve wrong data.
    
    For safety, consider invalid instruction syndrome as wrong memory access.
    
    Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
    Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
---
 xen/arch/arm/traps.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c
index f2ffcb7..2969039 100644
--- a/xen/arch/arm/traps.c
+++ b/xen/arch/arm/traps.c
@@ -1010,6 +1010,10 @@ static void do_trap_data_abort_guest(struct 
cpu_user_regs *regs,
     if ( rc == -EFAULT )
         goto bad_data_abort;
 
+    /* XXX: Decode the instruction if ISS is not valid */
+    if ( !dabt.valid )
+        goto bad_data_abort;
+
     if (handle_mmio(&info))
     {
         regs->pc += dabt.len ? 4 : 2;
--
generated by git-patchbot for /home/xen/git/xen.git#master

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