Re: UBSAN: Undefined behaviour in drivers/net/wireless/intel/iwlwifi/mvm/utils.c:838:5

[Luca Coelho <luca@coelho.fi>]

On Wed, 2017-12-20 at 12:00 +0100, Paul Menzel wrote:
> Dear Luca,
> 
> 
> Am 18.12.2017 um 19:30 schrieb Luca Coelho:
> > On Wed, 2017-12-13 at 16:32 +0200, Luciano Coelho wrote:
> > > On Wed, 2017-12-13 at 14:25 +0100, Paul Menzel wrote:
> > > > I enabled the undefined behavior sanitizer, and built Linus’ 
> > > > master branch under Ubuntu 17.10 with gcc (Ubuntu 7.2.0-
> > > > 8ubuntu3)
> > > > 7.2.0.
> > > > 
> > > > ``` $ grep UBSAN /boot/config-4.15.0-rc3+ 
> > > > CONFIG_ARCH_HAS_UBSAN_SANITIZE_ALL=y #
> > > > CONFIG_ARCH_WANTS_UBSAN_NO_NULL is not set CONFIG_UBSAN=y 
> > > > CONFIG_UBSAN_SANITIZE_ALL=y # CONFIG_UBSAN_ALIGNMENT is not
> > > > set 
> > > > CONFIG_UBSAN_NULL=y ```
> > > > 
> > > > Starting the system the messages below are printed.
> > > > 
> > > > Starting the system and using the wireless device shows the 
> > > > messages below.
> > > 
> > > Thanks for reporting! This shouldn't cause any problems, but I'll
> > > fix it by checking that the mac80211_queue is not INVALID_QUEUE
> > > (255) which seems to be the trigger for this warning.
> > 
> > Can you try the following patch to see if the problem goes away?
> > 
> > http://pastebin.coelho.fi/7b624f474846da52.txt
> 
> Thank you. The warning is gone now. Thank you.

Thanks for testing! We are actually improving the fix a bit, because it
seems that we should not have gotten INVALID_QUEUE there.  We will have
a two-fold fix (Sari, whom I CCed, is working on the other patch).


>  For the next time, it’d 
> be great to provide the output of `git format-patch -1`, which can
> be 
> applied with `git am`. The output of `git show` is with my knowledge 
> hard to apply.

Ah, sorry about that.  I didn't want to send a full patch here so that
it wouldn't get picked up by patchworks, so I just pastebinned it.

--
Luca.