On Mon 2022-05-23 12:39:12, Kees Cook wrote:

On Sat, May 21, 2022 at 11:07:52PM -0700, Christoph Hellwig wrote:

quoted

On Fri, May 20, 2022 at 02:06:56PM +0530, Maninder Singh wrote:

quoted

kallsyms functionality depends on KSYM_NAME_LEN directly.
but if user passed array length lesser than it, sprintf
can cause issues of buffer overflow attack.

So changing *sprint* and *lookup* APIs in this patch set
to have buffer size as an argument and replacing sprintf with
scnprintf.

This is still a pretty horrible API.  Passing something like
a struct seq_buf seems like the much better API here.  Also with
the amount of arguments and by reference passing it might be worth
to pass them as a structure while you're at it.

Yeah, I agree. It really seems like seq_buf would be nicer.

There is a new patchset that is trying to use this kind of buffer
in vsprintf.

It introduces another buffer struct because vsprintf() needs a bit
different semantic than the one used in seq_buf. But it actually
replaces seq_buf() in the end. I am not sure if this is the right
approach.

Anyway, the initial API is very simple, see
https://lore.kernel.org/r/20220604193042.1674951-2-kent.overstreet@gmail.com (local)

And it makes the internal vsprintf() API more sane, see
https://lore.kernel.org/r/20220604193042.1674951-4-kent.overstreet@gmail.com (local)

It would eventually solve also concerns about the kallsysms API.
Any comments on the new printbuf API are much appreaciated.

Best Regards,
Petr