On Thu, Apr 19 2018 at 6:04am -0400, Thomas Gleixner <[email protected]> wrote:
> From: Thomas Gleixner <[email protected]> > > The allocation of the reed solomon control structure can fail, but > fec_alloc_bufs() ignores that and subsequent operations in dm verity use > the potential NULL pointer unconditionally. > > Add a proper check and abort if init_rs() fails. This changelog makes little sense: init_rs() isn't in play relative to this patch. And it runs counter to this commit's changelog: commit 34c96507e8f6be497c15497be05f489fb34c5880 Author: NeilBrown <[email protected]> Date: Mon Apr 10 12:13:00 2017 +1000 dm verity fec: fix GFP flags used with mempool_alloc() mempool_alloc() cannot fail for GFP_NOIO allocation, so there is no point testing for failure. One place the code tested for failure was passing "0" as the GFP flags. This is most unusual and is probably meant to be GFP_NOIO, so that is changed. Also, allocation from ->extra_pool and ->prealloc_pool are repeated before releasing the previous allocation. This can deadlock if the code is servicing a write under high memory pressure. To avoid deadlocks, change these to use GFP_NOWAIT and leave the error handling in place. Signed-off-by: NeilBrown <[email protected]> Signed-off-by: Mike Snitzer <[email protected]> Seems there is no real need for this patch. Neil, what do you think? Thanks, Mike > Signed-off-by: Thomas Gleixner <[email protected]> > Cc: Boris Brezillon <[email protected]> > Cc: Tony Luck <[email protected]> > Cc: Kees Cook <[email protected]> > Cc: Segher Boessenkool <[email protected]> > Cc: Kernel Hardening <[email protected]> > Cc: Richard Weinberger <[email protected]> > Cc: Mike Snitzer <[email protected]> > Cc: Anton Vorontsov <[email protected]> > Cc: Colin Cross <[email protected]> > Cc: Andrew Morton <[email protected]> > Cc: David Woodhouse <[email protected]> > Cc: Alasdair Kergon <[email protected]> > > --- > drivers/md/dm-verity-fec.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > --- a/drivers/md/dm-verity-fec.c > +++ b/drivers/md/dm-verity-fec.c > @@ -308,8 +308,13 @@ static int fec_alloc_bufs(struct dm_veri > { > unsigned n; > > - if (!fio->rs) > + if (!fio->rs) { > fio->rs = mempool_alloc(v->fec->rs_pool, GFP_NOIO); > + if (!fio->rs) { > + DMERR("failed to allocate RS control structure"); > + return -ENOMEM; > + } > + } > > fec_for_each_prealloc_buffer(n) { > if (fio->bufs[n]) > > > > >
