[Xen-devel] [PATCH 2/4] arm: add bounds check on hypercall array

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

Otherwise a guest can cause us to run off the end of the array.

Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
---
 xen/arch/arm/traps.c |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c
index f2c25b5..6201d38 100644
--- a/xen/arch/arm/traps.c
+++ b/xen/arch/arm/traps.c
@@ -479,6 +479,12 @@ static void do_trap_hypercall(struct cpu_user_regs *regs, 
unsigned long iss)
         return;
     }
 
+    if ( regs->r12 > ARRAY_SIZE(arm_hypercall_table) )
+    {
+        regs->r0 = -ENOSYS;
+        return;
+    }
+
     call = arm_hypercall_table[regs->r12].fn;
     if ( call == NULL )
     {
-- 
1.7.9.1


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