linux-kernel - [PATCH] nvme: prevent double free in nvme_alloc

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Date:   Mon, 27 Apr 2020 14:34:41 +0200
From:   Niklas Cassel <niklas.cassel@....com>
To:     Keith Busch <kbusch@...nel.org>, Jens Axboe <axboe@...com>,
        Christoph Hellwig <hch@....de>,
        Sagi Grimberg <sagi@...mberg.me>,
        Igor Konopko <igor.j.konopko@...el.com>,
        Matias Bjørling <mb@...htnvm.io>,
        Javier González <javier@...xlabs.com>
Cc:     Niklas Cassel <niklas.cassel@....com>,
        Jens Axboe <axboe@...nel.dk>, linux-nvme@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] nvme: prevent double free in nvme_alloc_ns() error handling

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 <niklas.cassel@....com>
---
 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