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

BugLink: https://bugs.launchpad.net/bugs/1960566
[ 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>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

diff --git a/drivers/media/common/saa7146/saa7146_fops.c b/drivers/media/common/saa7146/saa7146_fops.c
index aabb830e746891a489d7f78dba39abb00b6e3fcb..4b332ea9861684cc5c57cb5aad3e1716df5355c0 100644 (file)
--- a/drivers/media/common/saa7146/saa7146_fops.c
+++ b/drivers/media/common/saa7146/saa7146_fops.c
@@ -525,7 +525,7 @@ 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 f962269306707179b992ee033d33e223c19c281a..86d4e2abed82acf83217f51abc0ee2bcea9f7db8 100644 (file)
--- a/drivers/media/pci/saa7146/hexium_gemini.c
+++ b/drivers/media/pci/saa7146/hexium_gemini.c
@@ -284,7 +284,12 @@ 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;