Re: kintegrityd workqueue fix backported, but only to some LTS

[Greg KH <gregkh@linuxfoundation.org>]

On Mon, Mar 14, 2022 at 01:08:57PM +0000, Niklas Cassel wrote:
> On Mon, Mar 14, 2022 at 01:28:38PM +0100, Greg KH wrote:
> > On Mon, Mar 14, 2022 at 11:50:18AM +0000, Niklas Cassel wrote:
> > > Hello Christoph, stable,
> > > 
> > > I recently saw a crash caused by the kintegrityd workqueue that could only
> > > be reproduced on older kernels.
> > > A null pointer dereference in function bio_integrity_verify_fn.
> > > 
> > > The fix in Linus's tree for this:
> > > 3df49967f6f1 ("block: flush the integrity workqueue in blk_integrity_unregister")
> > > was first merged in v5.15.
> > > 
> > > The fix has been backported to v5.10 LTS branch in:
> > > 1ef68b84bc11 ("block: flush the integrity workqueue in blk_integrity_unregister")
> > > 
> > > The fix doesn't have a fixes tag, but from inspecting the code,
> > > I don't understand why this was only backported to v5.10, AFAICT it should
> > > at least have been backported to v5.4, v4.19 and v4.14 LTS as well.
> > > 
> > > Original series:
> > > https://lore.kernel.org/all/20210914070657.87677-3-hch@lst.de/
> > > 
> > > The blk_flush_integrity() call that actually fixes the crash should be
> > > trivial to backport/add before clearing the flag and doing the memset.
> > 
> > A backported patch series would be great to have, to show that you have
> > tested that it works properly.
> 
> Hello Greg,
> 
> Unfortunately, I don't have access to the machine. I was only provided
> a kernel crash dump to diagnose the crash.
> 
> I guess I was hoping for someone more familiar with the integrity stuff
> to backport it. Both patch 1 and 3 are unrelated to the NULL pointer crash,
> and because of various refactoring, I'm not sure if patch 1 and 3 are even
> applicable for older kernel versions.

I do not know what patch 1 and 3 refer to here, sorry :(

greg k-h