[PATCH 05/22] audit: Fix sleep in atomic

[Jan Kara]

On Mon 26-12-16 11:33:10, Paul Moore wrote:
> On Fri, Dec 23, 2016 at 9:17 AM, Paul Moore <paul at paul-moore.com> wrote:
> > On Fri, Dec 23, 2016 at 8:24 AM, Jan Kara <jack at suse.cz> wrote:
> >> On Thu 22-12-16 18:18:36, Paul Moore wrote:
> >>> On Thu, Dec 22, 2016 at 4:15 AM, Jan Kara <jack at suse.cz> wrote:
> >>> > Audit tree code was happily adding new notification marks while holding
> >>> > spinlocks. Since fsnotify_add_mark() acquires group->mark_mutex this can
> >>> > lead to sleeping while holding a spinlock, deadlocks due to lock
> >>> > inversion, and probably other fun. Fix the problem by acquiring
> >>> > group->mark_mutex earlier.
> >>> >
> >>> > CC: Paul Moore <paul at paul-moore.com>
> >>> > Signed-off-by: Jan Kara <jack at suse.cz>
> >>> > ---
> >>> >  kernel/audit_tree.c | 13 +++++++++++--
> >>> >  1 file changed, 11 insertions(+), 2 deletions(-)
> >>>
> >>> [SIDE NOTE: this patch explains your comments and my earlier concern
> >>> about the locked/unlocked variants of fsnotify_add_mark() in
> >>> untag_chunk()]
> >>>
> >>> Ouch.  Thanks for catching this ... what is your goal with these
> >>> patches, are you targeting this as a fix during the v4.10-rcX cycle?
> >>> If not, any objections if I pull this patch into the audit tree and
> >>> send this to Linus during the v4.10-rcX cycle (assuming it passes
> >>> testing, yadda yadda)?
> >>
> >> Sure, go ahead. I plan these patches for the next merge window. So I can
> >> rebase the series once you merge audit fixes...
> >
> > Okay, great.  I'll merge this patch in the audit/stable-4.10 branch
> > for Linus but there will likely be some delays due to
> > holidays/vacation on my end.
> >
> > Thanks again for your help fixing this, I really appreciate it.
> 
> I merged this patch, as well as the "Remove fsnotify_duplicate_mark()"
> patch (to make things cleaner when merging this patch) and did a quick
> test using the audit-testsuite ... the test hung on the "file_create"
> tests.  Unfortunately, I'm traveling right now for the holidays and
> will not likely have a chance to debug this much further until after
> the new year, but I thought I would mention it in case you had some
> time to look into this failure.
> 
> For reference, here is the audit-testsuite again:
> 
> * https://github.com/linux-audit/audit-testsuite
> 
> ... and if you have a Fedora test system, here is the Rawhide kernel I
> used to test (it is basically my kernel-secnext test kernel with those
> two patches mentioned above added on top):
> 
> * https://copr.fedorainfracloud.org/coprs/pcmoore/kernel-testing/build/492386

So I found where the problem was. Attached is a new version of the patch.
Tests from audit-testsuite fail for me but do not hang anymore. I guess the
failing is because I don't have audit or selinux configured in any way and
I'm using SUSE I guess (if there's some easy way to do that, I'd be
interested) - runtests.pl complains that I have to be root although I am...

								Honza
-- 
Jan Kara <jack at suse.com>
SUSE Labs, CR
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 0001-audit-Fix-sleep-in-atomic.patch
Type: text/x-patch
Size: 3764 bytes
Desc: not available
URL: <http://listman.redhat.com/archives/linux-audit/attachments/20170102/cefa9205/attachment.bin>