Ondrej Mosnacek
ee0c54cfe3
[ Upstream commitf1aa2eb5ea] Currently proc_dobool expects a (bool *) in table->data, but sizeof(int) in table->maxsize, because it uses do_proc_dointvec() directly. This is unsafe for at least two reasons: 1. A sysctl table definition may use { .data = &variable, .maxsize = sizeof(variable) }, not realizing that this makes the sysctl unusable (see the Fixes: tag) and that they need to use the completely counterintuitive sizeof(int) instead. 2. proc_dobool() will currently try to parse an array of values if given .maxsize >= 2*sizeof(int), but will try to write values of type bool by offsets of sizeof(int), so it will not work correctly with neither an (int *) nor a (bool *). There is no .maxsize validation to prevent this. Fix this by: 1. Constraining proc_dobool() to allow only one value and .maxsize == sizeof(bool). 2. Wrapping the original struct ctl_table in a temporary one with .data pointing to a local int variable and .maxsize set to sizeof(int) and passing this one to proc_dointvec(), converting the value to/from bool as needed (using proc_dou8vec_minmax() as an example). 3. Extending sysctl_check_table() to enforce proc_dobool() expectations. 4. Fixing the proc_dobool() docstring (it was just copy-pasted from proc_douintvec, apparently...). 5. Converting all existing proc_dobool() users to set .maxsize to sizeof(bool) instead of sizeof(int). Fixes:83efeeeb3d("tty: Allow TIOCSTI to be disabled") Fixes:a2071573d6("sysctl: introduce new proc handler proc_dobool") Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com> Acked-by: Kees Cook <keescook@chromium.org> Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.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 Restructured Text 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.