On Sun, May 26 2019 at 8:50pm -0400, Gen Zhang <[email protected]> wrote:
> In function __rh_alloc(), the pointer nreg is allocated a memory space > via kmalloc(). And it is used in the following codes. However, when > there is a memory allocation error, kmalloc() fails. Thus null pointer > dereference may happen. And it will cause the kernel to crash. Therefore, > we should check the return value and handle the error. > Further, in __rh_find(), we should also check the return value and > handle the error. > > Signed-off-by: Gen Zhang <[email protected]> > --- > diff --git a/drivers/md/dm-region-hash.c b/drivers/md/dm-region-hash.c > index 1f76045..2fa1641 100644 > --- a/drivers/md/dm-region-hash.c > +++ b/drivers/md/dm-region-hash.c > @@ -290,8 +290,11 @@ static struct dm_region *__rh_alloc(struct > dm_region_hash *rh, region_t region) > struct dm_region *reg, *nreg; > > nreg = mempool_alloc(&rh->region_pool, GFP_ATOMIC); > - if (unlikely(!nreg)) > + if (unlikely(!nreg)) { > nreg = kmalloc(sizeof(*nreg), GFP_NOIO | __GFP_NOFAIL); > + if (!nreg) > + return NULL; > + } > > nreg->state = rh->log->type->in_sync(rh->log, region, 1) ? > DM_RH_CLEAN : DM_RH_NOSYNC; This patch isn't needed. __GFP_NOFAIL means the allocation won't fail. And there are many other users of __GFP_NOFAIL that don't check for failure. Mike
