Messages in this thread | | | Date | Thu, 5 Jul 2018 09:21:30 +0200 | From | Ingo Molnar <> | Subject | Re: set_memory_* (was: Re: BUG: unable to handle kernel paging request in bpf_int_jit_compile) |
| |
* Kees Cook <keescook@chromium.org> wrote:
> On Tue, Jun 26, 2018 at 3:53 PM, Daniel Borkmann <daniel@iogearbox.net> wrote: > > In any case, for pairs like set_memory_ro() + set_memory_rw() that are also used > > outside of bpf e.g. STRICT_MODULE_RWX and friends which are mostly default these > > days for some archs, is the choice to not check errors from there by design or from > > historical context that it originated from 'debugging code' in that sense (DEBUG_RODATA / > > DEBUG_SET_MODULE_RONX) earlier? Also if no-one checks for errors (and if that would > > infact be the recommendation it is agreed upon) should the API be changed to void, > > or generally should actual error checking occur on these + potential rollback; but > > then question is what about restoring part from prior set_memory_ro() via set_memory_rw()? > > Kees/others, do you happen to have some more context on recommended use around this > > by any chance? (Would probably also help if we add some doc around assumptions into > > include/linux/set_memory.h for future users.) > > If set_memory_* can fail, I think it needs to be __must_check, and all > the callers need to deal with it gracefully. Those markings aren't > "advisory": they're expected to actually do what they say.
Yes - but there's probably a few exceptions like early init code where the calls not succeeding are signs of bugs - so any error return should probably be WARN_ON()ed about.
Thanks,
Ingo
| |