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For interrupts from badly behaved hardware (as emulated by Syzbot), it is possible for the Comedi core functions that manage the progress of asynchronous data acquisition to be called from driver ISRs while no asynchronous command has been set up, which can cause problems such as invalid pointer dereferencing or dividing by zero. Change those functions in the Comedi core to use this pattern: if `comedi_get_is_subdevice_running(s)` returns `true` then call a safe version of the function with the same name prefixed with an underscore, followed by a call to `comedi_put_is_subdevice_running(s)`, otherwise take some default action. `comedi_get_is_subdevice_running(s)` returning `true` ensures that the details of the asynchronous command will not be destroyed before the matching call to `comedi_put_is_subdevice_running(s)`. Replace calls to those functions from elsewhere in the Comedi core with calls to the safe versions of the functions. The modified functions are: `comedi_buf_read_alloc()`, `comedi_buf_read_free()`, `comedi_buf_read_n_available()`, `comedi_buf_read_samples()`, `comedi_buf_write_alloc()`, `comedi_buf_write_free()`, `comedi_buf_write_samples()`, `comedi_bytes_per_scan()`, `comedi_event()`, `comedi_handle_events()`, `comedi_inc_scan_progress()`, `comedi_nsamples_left()`, `comedi_nscans_left()`. Signed-off-by: Ian Abbott <abbotti@mev.co.uk> Link: https://patch.msgid.link/20251023133001.8439-3-abbotti@mev.co.uk Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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.