media: cx25821: prevent out-of-bounds read on array card

BugLink: http://bugs.launchpad.net/bugs/1783418
[ Upstream commit 67300abdbe9f1717532aaf4e037222762716d0f6 ]

Currently an out of range dev->nr is detected by just reporting the
issue and later on an out-of-bounds read on array card occurs because
of this. Fix this by checking the upper range of dev->nr with the size
of array card (removes the hard coded size), move this check earlier
and also exit with the error -ENOSYS to avoid the later out-of-bounds
array read.

Detected by CoverityScan, CID#711191 ("Out-of-bounds-read")

Fixes: commit 02b20b0b4cde ("V4L/DVB (12730): Add conexant cx25821 driver")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
[hans.verkuil@cisco.com: %ld -> %zd]
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/drivers/media/pci/cx25821/cx25821-core.c b/drivers/media/pci/cx25821/cx25821-core.c
index 04aa4a68a0aefa11132182e56d7231122158b93e..040c6c251d3a34c00e33c1c2ef42e5e28abef0cd 100644 (file)
--- a/drivers/media/pci/cx25821/cx25821-core.c
+++ b/drivers/media/pci/cx25821/cx25821-core.c
@@ -867,6 +867,10 @@ static int cx25821_dev_setup(struct cx25821_dev *dev)
        dev->nr = ++cx25821_devcount;
        sprintf(dev->name, "cx25821[%d]", dev->nr);
 
+       if (dev->nr >= ARRAY_SIZE(card)) {
+               CX25821_INFO("dev->nr >= %zd", ARRAY_SIZE(card));
+               return -ENODEV;
+       }
        if (dev->pci->device != 0x8210) {
                pr_info("%s(): Exiting. Incorrect Hardware device = 0x%02x\n",
                        __func__, dev->pci->device);
@@ -882,9 +886,6 @@ static int cx25821_dev_setup(struct cx25821_dev *dev)
                dev->channels[i].sram_channels = &cx25821_sram_channels[i];
        }
 
-       if (dev->nr > 1)
-               CX25821_INFO("dev->nr > 1!");
-
        /* board config */
        dev->board = 1;         /* card[dev->nr]; */
        dev->_max_num_decoders = MAX_DECODERS;