tracing/stack-tracer: avoid races accessing file
Impact: fix race
vma->vm_file reference is only stable while holding the mmap_sem,
so move usage of it to within the critical section.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 4c3bd82..48d1536 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1470,13 +1470,13 @@
file = vma->vm_file;
vmstart = vma->vm_start;
}
+ if (file) {
+ ret = trace_seq_path(s, &file->f_path);
+ if (ret)
+ ret = trace_seq_printf(s, "[+0x%lx]", ip - vmstart);
+ }
up_read(&mm->mmap_sem);
}
- if (file) {
- ret = trace_seq_path(s, &file->f_path);
- if (ret)
- ret = trace_seq_printf(s, "[+0x%lx]", ip - vmstart);
- }
if (ret && ((sym_flags & TRACE_ITER_SYM_ADDR) || !file))
ret = trace_seq_printf(s, " <" IP_FMT ">", ip);
return ret;