Re: [PATCH net] cfg80211: fix callback type mismatches in wext-compat

On Fri, 2020-11-20 at 11:26 -0800, Kees Cook wrote:

On Tue, Nov 17, 2020 at 02:07:43PM -0800, Sami Tolvanen wrote:

quoted

On Tue, Nov 17, 2020 at 1:45 PM Kees Cook [off-list ref] wrote:

quoted

On Tue, Nov 17, 2020 at 12:59:02PM -0800, Sami Tolvanen wrote:

quoted

Instead of casting callback functions to type iw_handler, which trips
indirect call checking with Clang's Control-Flow Integrity (CFI), add
stub functions with the correct function type for the callbacks.

Oh, wow. iw_handler with union iwreq_data look like really nasty hacks.
Aren't those just totally bypassing type checking? Where do the
callbacks actually happen? I couldn't find them...

The callbacks to these happen in ioctl_standard_call in wext-core.c.

Thanks! If this is all the 'old compat' code, this patch looks fine. I
think new stuff should probably encode types in some fashion (rather
than via wrappers).

Everything mentioning wext has been deprecated for something like 15
years ... so yeah. But people still use it :(

johannes