arm64: ptrace: fix compat registes get/set to be endian clean

On a BE system the wrong half of the X registers is retrieved/written
when attempting to get/set the value of aarch32 registers through
ptrace.

Ensure that types are the correct width so that the relevant
casting occurs.

Signed-off-by: Matthew Leach <matthew.leach@arm.com>
Reviewed-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

1 files changed, 19 insertions, 21 deletions

diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
index fecdbf7de82e..6777a2192b83 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -636,28 +636,27 @@ static int compat_gpr_get(struct task_struct *target,
 
         for (i = 0; i < num_regs; ++i) {
                 unsigned int idx = start + i;
-                void *reg;
+                compat_ulong_t reg;
 
                 switch (idx) {
                 case 15:
-                        reg = (void *)&task_pt_regs(target)->pc;
+                        reg = task_pt_regs(target)->pc;
                         break;
                 case 16:
-                        reg = (void *)&task_pt_regs(target)->pstate;
+                        reg = task_pt_regs(target)->pstate;
                         break;
                 case 17:
-                        reg = (void *)&task_pt_regs(target)->orig_x0;
+                        reg = task_pt_regs(target)->orig_x0;
                         break;
                 default:
-                        reg = (void *)&task_pt_regs(target)->regs[idx];
+                        reg = task_pt_regs(target)->regs[idx];
                 }
 
-                ret = copy_to_user(ubuf, reg, sizeof(compat_ulong_t));
-
+                ret = copy_to_user(ubuf, &reg, sizeof(reg));
                 if (ret)
                         break;
-                else
-                        ubuf += sizeof(compat_ulong_t);
+
+                ubuf += sizeof(reg);
         }
 
         return ret;
@@ -685,28 +684,28 @@ static int compat_gpr_set(struct task_struct *target,
 
         for (i = 0; i < num_regs; ++i) {
                 unsigned int idx = start + i;
-                void *reg;
+                compat_ulong_t reg;
+
+                ret = copy_from_user(&reg, ubuf, sizeof(reg));
+                if (ret)
+                        return ret;
+
+                ubuf += sizeof(reg);
 
                 switch (idx) {
                 case 15:
-                        reg = (void *)&newregs.pc;
+                        newregs.pc = reg;
                         break;
                 case 16:
-                        reg = (void *)&newregs.pstate;
+                        newregs.pstate = reg;
                         break;
                 case 17:
-                        reg = (void *)&newregs.orig_x0;
+                        newregs.orig_x0 = reg;
                         break;
                 default:
-                        reg = (void *)&newregs.regs[idx];
+                        newregs.regs[idx] = reg;
                 }
 
-                ret = copy_from_user(reg, ubuf, sizeof(compat_ulong_t));
-
-                if (ret)
-                        goto out;
-                else
-                        ubuf += sizeof(compat_ulong_t);
         }
 
         if (valid_user_regs(&newregs.user_regs))
@@ -714,7 +713,6 @@ static int compat_gpr_set(struct task_struct *target,
         else
                 ret = -EINVAL;
 
-out:
         return ret;
 }