nios2: traced syscall does need to check the syscall number

all checks done before letting the tracer modify the register
state are worthless...

Fixes: 82ed08dd1b0e ("nios2: Exception handling")
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Dinh Nguyen <dinguyen@kernel.org>

diff --git a/arch/nios2/kernel/entry.S b/arch/nios2/kernel/entry.S
index 8f41ef5..fd24490 100644 (file)
--- a/arch/nios2/kernel/entry.S
+++ b/arch/nios2/kernel/entry.S
@@ -255,9 +255,9 @@ traced_system_call:
        ldw     r6, PT_R6(sp)
        ldw     r7, PT_R7(sp)
 
-       /* Fetch the syscall function, we don't need to check the boundaries
-        * since this is already done.
-        */
+       /* Fetch the syscall function. */
+       movui   r1, __NR_syscalls
+       bgeu    r2, r1, traced_invsyscall
        slli    r1, r2, 2
        movhi   r11,%hiadj(sys_call_table)
        add     r1, r1, r11
@@ -287,6 +287,11 @@ end_translate_rc_and_ret2:
        RESTORE_SWITCH_STACK
        br      ret_from_exception
 
+       /* If the syscall number was invalid return ENOSYS */
+traced_invsyscall:
+       movi    r2, -ENOSYS
+       br      translate_rc_and_ret2
+
 Luser_return:
        GET_THREAD_INFO r11                     /* get thread_info pointer */
        ldw     r10, TI_FLAGS(r11)              /* get thread_info->flags */