[PATCH 5.15 111/244] nios2: traced syscall does need to check the syscall number

Greg Kroah-Hartman
2022-08-23T10:06:45Z

From: Al Viro <viro@zeniv.linux.org.uk>

commit 25ba820ef36bdbaf9884adeac69b6e1821a7df76 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/nios2/kernel/entry.S | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)

--- 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 */