media: saa7146: hexium_gemini: Fix a NULL pointer dereference in hexium_attach()

[ Upstream commit 3af86b046933ba513d08399dba0d4d8b50d607d0 ]

In hexium_attach(dev, info), saa7146_vv_init() is called to allocate
a new memory for dev->vv_data. saa7146_vv_release() will be called on
failure of saa7146_register_device(). There is a dereference of
dev->vv_data in saa7146_vv_release(), which could lead to a NULL
pointer dereference on failure of saa7146_vv_init().

Fix this bug by adding a check of saa7146_vv_init().

This bug was found by a static analyzer. The analysis employs
differential checking to identify inconsistent security operations
(e.g., checks or kfrees) between two code paths and confirms that the
inconsistent operations are not recovered in the current function or
the callers, so they constitute bugs.

Note that, as a bug found by static analysis, it can be a false
positive or hard to trigger. Multiple researchers have cross-reviewed
the bug.

Builds with CONFIG_VIDEO_HEXIUM_GEMINI=m show no new warnings,
and our static analyzer no longer warns about this code.

Link: https://lore.kernel.org/linux-media/20211203154030.111210-1-zhou1615@umn.edu
Signed-off-by: Zhou Qingyang <zhou1615@umn.edu>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/media/common/saa7146/saa7146_fops.c b/drivers/media/common/saa7146/saa7146_fops.c
index 930d2c94d5d30458b7ef40ad72a5155454613516..2c9365a39270ad67f0e60f19f77d6d022eb5d7ea 100644 (file)
--- a/drivers/media/common/saa7146/saa7146_fops.c
+++ b/drivers/media/common/saa7146/saa7146_fops.c
@@ -524,7 +524,7 @@ int saa7146_vv_init(struct saa7146_dev* dev, struct saa7146_ext_vv *ext_vv)
                ERR("out of memory. aborting.\n");
                kfree(vv);
                v4l2_ctrl_handler_free(hdl);
-               return -1;
+               return -ENOMEM;
        }
 
        saa7146_video_uops.init(dev,vv);

diff --git a/drivers/media/pci/saa7146/hexium_gemini.c b/drivers/media/pci/saa7146/hexium_gemini.c
index a527d86b93a77b9f60a94dc884a22b9b43bd6c39..7f498aebb411261863d38cc645987b7a0dc15ed6 100644 (file)
--- a/drivers/media/pci/saa7146/hexium_gemini.c
+++ b/drivers/media/pci/saa7146/hexium_gemini.c
@@ -296,7 +296,12 @@ static int hexium_attach(struct saa7146_dev *dev, struct saa7146_pci_extension_d
        hexium_set_input(hexium, 0);
        hexium->cur_input = 0;
 
-       saa7146_vv_init(dev, &vv_data);
+       ret = saa7146_vv_init(dev, &vv_data);
+       if (ret) {
+               i2c_del_adapter(&hexium->i2c_adapter);
+               kfree(hexium);
+               return ret;
+       }
 
        vv_data.vid_ops.vidioc_enum_input = vidioc_enum_input;
        vv_data.vid_ops.vidioc_g_input = vidioc_g_input;