[Xen-changelog] [xen stable-4.4] xen: arm: handle AArch32 userspace when dumping 64-bit guest state.

[patchbot@xxxxxxx]

commit 99a9f497cb070ba7168d45442ad8ea3604d95dcb
Author:     Ian Campbell <ian.campbell@xxxxxxxxxx>
AuthorDate: Tue Aug 12 15:45:49 2014 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue Aug 12 15:45:49 2014 +0200

    xen: arm: handle AArch32 userspace when dumping 64-bit guest state.
    
    A 64-bit guest can still be in 32-bit mode when running userspace,
    handle this case by dumping the correct 32-bit state.
    
    Note that on ARM it is not possible to change mode without the help
    of the next exception level, hence there is no way a 64-bit guest can
    be running in 32-bit kernel modes.
    
    This is part of CVE-2014-5147 / XSA-102.
    
    Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
    Acked-by: Julien Grall <julien.grall@xxxxxxxxxx>
    master commit: fc0cafeab30fe93963457fafbad7a01c7f55ea5f
    master date: 2014-08-12 15:32:27 +0200
---
 xen/arch/arm/traps.c |   12 +++++++++++-
 1 files changed, 11 insertions(+), 1 deletions(-)

diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c
index e2e2db3..7367399 100644
--- a/xen/arch/arm/traps.c
+++ b/xen/arch/arm/traps.c
@@ -697,7 +697,17 @@ static void _show_registers(struct cpu_user_regs *regs,
             show_registers_32(regs, ctxt, guest_mode, v);
 #ifdef CONFIG_ARM_64
         else if ( is_pv64_domain(v->domain) )
-            show_registers_64(regs, ctxt, guest_mode, v);
+        {
+            if ( psr_mode_is_32bit(regs->cpsr) )
+            {
+                BUG_ON(!usr_mode(regs));
+                show_registers_32(regs, ctxt, guest_mode, v);
+            }
+            else
+            {
+                show_registers_64(regs, ctxt, guest_mode, v);
+            }
+        }
 #endif
     }
     else
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.4

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