[PATCH 4.12 087/196] s390/syscalls: Fix out of bounds arguments access

[Greg Kroah-Hartman]

4.12-stable review patch.  If anyone has any objections, please let me know.

--

From: Jiri Olsa 

commit c46fc0424ced3fb71208e72bd597d91b9169a781 upstream.

Zorro reported following crash while having enabled
syscall tracing (CONFIG_FTRACE_SYSCALLS):

  Unable to handle kernel pointer dereference at virtual ...
  Oops: 0011 [#1] SMP DEBUG_PAGEALLOC

  SNIP

  Call Trace:
  ([<0024d79c>] ftrace_syscall_enter+0xec/0x1d8)
   [<001099c6>] do_syscall_trace_enter+0x236/0x2f8
   [<00730f1c>] sysc_tracesys+0x1a/0x32
   [<03fffcf946a2>] 0x3fffcf946a2
  INFO: lockdep is turned off.
  Last Breaking-Event-Address:
   [<0022dd44>] rb_event_data+0x34/0x40
  ---[ end trace 8c795f86b1b3f7b9 ]---

The crash happens in syscall_get_arguments function for
syscalls with zero arguments, that will try to access
first argument (args[0]) in event entry, but it's not
allocated.

Bail out of there are no arguments.

Reported-by: Zorro Lang 
Signed-off-by: Jiri Olsa 
Signed-off-by: Martin Schwidefsky 
Signed-off-by: Greg Kroah-Hartman 

---
 arch/s390/include/asm/syscall.h |6 ++
 1 file changed, 6 insertions(+)

--- a/arch/s390/include/asm/syscall.h
+++ b/arch/s390/include/asm/syscall.h
@@ -64,6 +64,12 @@ static inline void syscall_get_arguments
 {
unsigned long mask = -1UL;
 
+   /*
+* No arguments for this syscall, there's nothing to do.
+*/
+   if (!n)
+   return;
+
BUG_ON(i + n > 6);
 #ifdef CONFIG_COMPAT
if (test_tsk_thread_flag(task, TIF_31BIT))

[PATCH 4.12 087/196] s390/syscalls: Fix out of bounds arguments access

[Greg Kroah-Hartman]

4.12-stable review patch.  If anyone has any objections, please let me know.

--

From: Jiri Olsa 

commit c46fc0424ced3fb71208e72bd597d91b9169a781 upstream.

Zorro reported following crash while having enabled
syscall tracing (CONFIG_FTRACE_SYSCALLS):

  Unable to handle kernel pointer dereference at virtual ...
  Oops: 0011 [#1] SMP DEBUG_PAGEALLOC

  SNIP

  Call Trace:
  ([<0024d79c>] ftrace_syscall_enter+0xec/0x1d8)
   [<001099c6>] do_syscall_trace_enter+0x236/0x2f8
   [<00730f1c>] sysc_tracesys+0x1a/0x32
   [<03fffcf946a2>] 0x3fffcf946a2
  INFO: lockdep is turned off.
  Last Breaking-Event-Address:
   [<0022dd44>] rb_event_data+0x34/0x40
  ---[ end trace 8c795f86b1b3f7b9 ]---

The crash happens in syscall_get_arguments function for
syscalls with zero arguments, that will try to access
first argument (args[0]) in event entry, but it's not
allocated.

Bail out of there are no arguments.

Reported-by: Zorro Lang 
Signed-off-by: Jiri Olsa 
Signed-off-by: Martin Schwidefsky 
Signed-off-by: Greg Kroah-Hartman 

---
 arch/s390/include/asm/syscall.h |6 ++
 1 file changed, 6 insertions(+)

--- a/arch/s390/include/asm/syscall.h
+++ b/arch/s390/include/asm/syscall.h
@@ -64,6 +64,12 @@ static inline void syscall_get_arguments
 {
unsigned long mask = -1UL;
 
+   /*
+* No arguments for this syscall, there's nothing to do.
+*/
+   if (!n)
+   return;
+
BUG_ON(i + n > 6);
 #ifdef CONFIG_COMPAT
if (test_tsk_thread_flag(task, TIF_31BIT))