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([199.182.234.55]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-82f0c4b17fcsm5949399b3a.33.2026.04.11.07.57.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 11 Apr 2026 07:57:46 -0700 (PDT) From: Guangshuo Li To: Dan Williams , Vishal Verma , Dave Jiang , Andrew Morton , nvdimm@lists.linux.dev, linux-cxl@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Guangshuo Li , stable@vger.kernel.org Subject: [PATCH] device-dax: Fix refcount leak in __devm_create_dev_dax() error path Date: Sat, 11 Apr 2026 22:57:26 +0800 Message-ID: <20260411145726.2299438-1-lgs201920130244@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" After device_initialize(), the lifetime of the embedded struct device is expected to be managed through the device core reference counting. In __devm_create_dev_dax(), several failure paths after device_initialize() free dev_dax directly instead of releasing the device reference with put_device(). This bypasses the normal device lifetime rules and may leave the reference count of the embedded struct device unbalanced, resulting in a refcount leak and potentially leading to a use-after-free. Fix this by assigning dev->type before device_initialize(), so the release callback is available for put_device(), and use put_device() in the post-initialization error paths. Keep dev_dax range cleanup explicit in the error path. Fixes: c2f3011ee697f ("device-dax: add an allocation interface for device-d= ax instances") Cc: stable@vger.kernel.org Signed-off-by: Guangshuo Li --- drivers/dax/bus.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c index fde29e0ad68b..8753115cd371 100644 --- a/drivers/dax/bus.c +++ b/drivers/dax/bus.c @@ -1453,6 +1453,7 @@ static struct dev_dax *__devm_create_dev_dax(struct d= ev_dax_data *data) } =20 dev =3D &dev_dax->dev; + dev->type =3D &dev_dax_type; device_initialize(dev); dev_set_name(dev, "dax%d.%d", dax_region->id, dev_dax->id); =20 @@ -1499,7 +1500,6 @@ static struct dev_dax *__devm_create_dev_dax(struct d= ev_dax_data *data) dev->devt =3D inode->i_rdev; dev->bus =3D &dax_bus_type; dev->parent =3D parent; - dev->type =3D &dev_dax_type; =20 rc =3D device_add(dev); if (rc) { @@ -1523,14 +1523,21 @@ static struct dev_dax *__devm_create_dev_dax(struct= dev_dax_data *data) =20 err_alloc_dax: kfree(dev_dax->pgmap); + dev_dax->pgmap =3D NULL; + err_pgmap: free_dev_dax_ranges(dev_dax); + put_device(dev); + return ERR_PTR(rc); + err_range: - free_dev_dax_id(dev_dax); + put_device(dev); + return ERR_PTR(rc); + err_id: kfree(dev_dax); - return ERR_PTR(rc); + } =20 struct dev_dax *devm_create_dev_dax(struct dev_dax_data *data) --=20 2.43.0