On 27.04.2020 18:22, Niklas Cassel wrote:
On Mon, Apr 27, 2020 at 08:03:11PM +0200, Javier González wrote:On 27.04.2020 14:34, Niklas Cassel wrote: > When jumping to the out_put_disk label, we will call put_disk(), which will > trigger a call to disk_release(), which calls blk_put_queue(). > > Later in the cleanup code, we do blk_cleanup_queue(), which will also call > blk_put_queue(). > > Putting the queue twice is incorrect, and will generate a KASAN splat. > > Set the disk->queue pointer to NULL, before calling put_disk(), so that the > first call to blk_put_queue() will not free the queue. > > The second call to blk_put_queue() uses another pointer to the same queue, > so this call will still free the queue. > > Fixes: 85136c010285 ("lightnvm: simplify geometry enumeration") > Signed-off-by: Niklas Cassel <[email protected]> > --- > drivers/nvme/host/core.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c > index 91c1bd659947..f2adea96b04c 100644 > --- a/drivers/nvme/host/core.c > +++ b/drivers/nvme/host/core.c > @@ -3642,6 +3642,8 @@ static void nvme_alloc_ns(struct nvme_ctrl *ctrl, unsigned nsid) > > return; > out_put_disk: > + /* prevent double queue cleanup */ > + ns->disk->queue = NULL; > put_disk(ns->disk); > out_unlink_ns: > mutex_lock(&ctrl->subsys->lock); > -- > 2.25.3 > What about delaying the assignment of ns->disk?diff --git i/drivers/nvme/host/core.c w/drivers/nvme/host/core.c index a4d8c90ee7cc..6da4a9ced945 100644 --- i/drivers/nvme/host/core.c +++ w/drivers/nvme/host/core.c @@ -3541,7 +3541,6 @@ static int nvme_alloc_ns(struct nvme_ctrl *ctrl, unsigned nsid) disk->queue = ns->queue; disk->flags = flags; memcpy(disk->disk_name, disk_name, DISK_NAME_LEN); - ns->disk = disk; __nvme_revalidate_disk(disk, id); @@ -3553,6 +3552,8 @@ static int nvme_alloc_ns(struct nvme_ctrl *ctrl, unsigned nsid) } } + ns->disk = disk; +Hello Javier! The only case where we jump to the out_put_disk label, is if the nvme_nvm_register() call failed. In that case, we want to undo the alloc_disk_node() operation, i.e., decrease the refcount. If we don't set "ns->disk = disk;" before the call to nvme_nvm_register(), then, if register fails, and we jump to the put_disk(ns->disk) label, ns->disk will be NULL, so the recount will not be decreased, so I assume that this memory would then be a memory leak. I think that the problem is that the block functions are a bit messy. Most drivers seem to do blk_cleanup_queue() first and then do put_disk(), but some drivers do it in the opposite way, so I think that we might have some more use-after-free bugs in some of these drivers that do it in the opposite way.
Hi Niklas, Yes, the out_put_disk label was introduced at the same time as the LightNVM entry point. We can do a better job at separating the cleanup functions, but as far as I can see ns->disk is not used in the LightNVM initialization, so delaying the initialization should be ok. Part of this should be also changing the out_put_disk to put_disk(disk). Note that initializing other namespace types here do not require ns->disk either, so delaying initialization should be ok. We have been running with this patch locally for some time. This said, this is an alternative as your fix works. Javier
