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([2001:250:5800:1000::5a26]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2b97aaaf65fsm30416065ad.31.2026.04.28.08.49.33 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 28 Apr 2026 08:49:37 -0700 (PDT) From: Guangshuo Li To: Yishai Hadas , Jason Gunthorpe , Leon Romanovsky , Jack Morgenstein , Roland Dreier , linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Guangshuo Li , stable@vger.kernel.org Subject: [PATCH v3] IB/mlx4: Fix refcount leak in add_port() error path Date: Tue, 28 Apr 2026 23:47:16 +0800 Message-ID: <20260428154716.375069-1-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 kobject_init_and_add(), the lifetime of the embedded struct kobject is expected to be managed through the kobject core reference counting. In add_port(), if kobject_init_and_add() fails, the error path frees p directly instead of releasing the kobject reference with kobject_put(). This may leave the reference count of the embedded struct kobject unbalanced, resulting in a refcount leak and potentially leading to a use-after-free. The issue was identified by a static analysis tool I developed and confirmed by manual review. Fix this by using kobject_put(&p->kobj) in the kobject_init_and_add() failure path. Fixes: c1e7e466120b ("IB/mlx4: Add iov directory in sysfs under the ib devi= ce") Cc: stable@vger.kernel.org Signed-off-by: Guangshuo Li --- v3: - make mlx4_port_release() tolerate NULL attribute arrays - drop the parent kobject reference on the kobject_init_and_add() failure path before putting the embedded kobject v2: - note that the issue was identified by my static analysis tool - and confirmed by manual review drivers/infiniband/hw/mlx4/sysfs.c | 25 ++++++++++++++++++------- 1 file changed, 18 insertions(+), 7 deletions(-) diff --git a/drivers/infiniband/hw/mlx4/sysfs.c b/drivers/infiniband/hw/mlx= 4/sysfs.c index b8fa4ecfc961..38c64b5fb23a 100644 --- a/drivers/infiniband/hw/mlx4/sysfs.c +++ b/drivers/infiniband/hw/mlx4/sysfs.c @@ -380,12 +380,17 @@ static void mlx4_port_release(struct kobject *kobj) struct attribute *a; int i; =20 - for (i =3D 0; (a =3D p->pkey_group.attrs[i]); ++i) - kfree(a); - kfree(p->pkey_group.attrs); - for (i =3D 0; (a =3D p->gid_group.attrs[i]); ++i) - kfree(a); - kfree(p->gid_group.attrs); + if (p->pkey_group.attrs) { + for (i =3D 0; (a =3D p->pkey_group.attrs[i]); ++i) + kfree(a); + kfree(p->pkey_group.attrs); + } + + if (p->gid_group.attrs) { + for (i =3D 0; (a =3D p->gid_group.attrs[i]); ++i) + kfree(a); + kfree(p->gid_group.attrs); + } kfree(p); } =20 @@ -640,7 +645,7 @@ static int add_port(struct mlx4_ib_dev *dev, int port_n= um, int slave) kobject_get(dev->dev_ports_parent[slave]), "%d", port_num); if (ret) - goto err_alloc; + goto err_kobj; =20 p->pkey_group.name =3D "pkey_idx"; p->pkey_group.attrs =3D @@ -687,6 +692,12 @@ static int add_port(struct mlx4_ib_dev *dev, int port_= num, int slave) kobject_put(dev->dev_ports_parent[slave]); kfree(p); return ret; + +err_kobj: + kobject_put(dev->dev_ports_parent[slave]); + kobject_put(&p->kobj); + return ret; + } =20 static int register_one_pkey_tree(struct mlx4_ib_dev *dev, int slave) --=20 2.43.0