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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/44c5deaa-b094-4852-90f9-52f3fb10e67a@stanley.mountain/ Reported-by: Dan Carpenter <dan.carpenter@linaro.org> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.