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:
([<000000000024d79c>] ftrace_syscall_enter+0xec/0x1d8)
[<00000000001099c6>] do_syscall_trace_enter+0x236/0x2f8
[<0000000000730f1c>] sysc_tracesys+0x1a/0x32
[<000003fffcf946a2>] 0x3fffcf946a2
INFO: lockdep is turned off.
Last Breaking-Event-Address:
[<000000000022dd44>] 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 <zlang@xxxxxxxxxx>
Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
---
arch/s390/include/asm/syscall.h | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/arch/s390/include/asm/syscall.h b/arch/s390/include/asm/syscall.h
index 6ba0bf928909..5f7c11c932fa 100644
--- a/arch/s390/include/asm/syscall.h
+++ b/arch/s390/include/asm/syscall.h
@@ -64,14 +64,22 @@ static inline void syscall_get_arguments(struct task_struct *task,
{
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))
mask = 0xffffffff;
#endif
- while (n-- > 0)
+ while (n-- > 0) {
if (i + n > 0)
args[n] = regs->gprs[2 + i + n] & mask;
+ }
+
if (i == 0)
args[0] = regs->orig_gpr2 & mask;
}
--
2.9.4
--
To unsubscribe from this list: send the line "unsubscribe linux-s390" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
