From: Steven Rostedt <[email protected]>
In allocate_trace_buffer() the following code:
buf->buffer = ring_buffer_alloc_range(size, rb_flags, 0,
tr->range_addr_start,
tr->range_addr_size,
struct_size(tscratch, entries, 128));
tscratch = ring_buffer_meta_scratch(buf->buffer, &scratch_size);
setup_trace_scratch(tr, tscratch, scratch_size);
has undefined behavior if ring_buffer_alloc_range() fails because
"scratch_size" is not initialize. If the allocation fails, then
buf->buffer will be NULL. The ring_buffer_meta_scratch() will return
NULL immediately if it is passed a NULL buffer and it will not update
scratch_size. Then setup_trace_scratch() will return immediately if
tscratch is NULL.
Although there's no real issue here, but it is considered undefined
behavior to pass an uninitialized variable to a function as input, and
UBSan may complain about it.
Just initialize scratch_size to zero to make the code defined behavior and
a little more robust.
Link:
https://lore.kernel.org/all/[email protected]/
Reported-by: Dan Carpenter <[email protected]>
Signed-off-by: Steven Rostedt (Google) <[email protected]>
---
kernel/trace/trace.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index c3c79908766e..66dc62233393 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -9387,7 +9387,7 @@ allocate_trace_buffer(struct trace_array *tr, struct
array_buffer *buf, int size
{
enum ring_buffer_flags rb_flags;
struct trace_scratch *tscratch;
- unsigned int scratch_size;
+ unsigned int scratch_size = 0;
rb_flags = tr->trace_flags & TRACE_ITER_OVERWRITE ? RB_FL_OVERWRITE : 0;
--
2.47.2
