On Sat July 7 2012 20:46:21 Hans de Goede wrote:
> Commit efbceecd4522a41b8442c6b4f68b4508d57d1ccf, adds a number of helper
> functions for ctrl related ioctls to v4l2-ioctl.c, these helpers assume that
> if file->private_data != NULL, it points to a v4l2_fh, which is only the case
> for drivers which actually use v4l2_fh.
>
> This breaks for example bttv which use the "filedata" pointer for its own uses,
> and now all the ctrl ioctls try to use whatever its filedata points to as
> v4l2_fh and think it has a ctrl_handler, leading to:
>
> [ 142.499214] BUG: unable to handle kernel NULL pointer dereference at 0000000000000021
> [ 142.499270] IP: [<ffffffffa01cb959>] v4l2_queryctrl+0x29/0x230 [videodev]
> [ 142.514649] [<ffffffffa01c7a77>] v4l_queryctrl+0x47/0x90 [videodev]
> [ 142.517417] [<ffffffffa01c58b1>] __video_do_ioctl+0x2c1/0x420 [videodev]
> [ 142.520116] [<ffffffffa01c7ee6>] video_usercopy+0x1a6/0x470 [videodev]
> ...
>
> This patch adds the missing test_bit(V4L2_FL_USES_V4L2_FH, &vfd->flags) tests
> to the ctrl ioctl helpers v4l2_fh paths, fixing the issues with for example
> the bttv driver.
Urgh, I didn't test with a 'old' driver. Thanks for catching this. But I would
prefer a simpler patch (although effectively the same) like this:
diff --git a/drivers/media/video/v4l2-ioctl.c b/drivers/media/video/v4l2-ioctl.c
index 70e0efb..bbcb4f6 100644
--- a/drivers/media/video/v4l2-ioctl.c
+++ b/drivers/media/video/v4l2-ioctl.c
@@ -1486,7 +1486,7 @@ static int v4l_queryctrl(const struct v4l2_ioctl_ops *ops,
{
struct video_device *vfd = video_devdata(file);
struct v4l2_queryctrl *p = arg;
- struct v4l2_fh *vfh = fh;
+ struct v4l2_fh *vfh = test_bit(V4L2_FL_USES_V4L2_FH, &vfd->flags) ? fh : NULL;
if (vfh && vfh->ctrl_handler)
return v4l2_queryctrl(vfh->ctrl_handler, p);
@@ -1502,7 +1502,7 @@ static int v4l_querymenu(const struct v4l2_ioctl_ops *ops,
{
struct video_device *vfd = video_devdata(file);
struct v4l2_querymenu *p = arg;
- struct v4l2_fh *vfh = fh;
+ struct v4l2_fh *vfh = test_bit(V4L2_FL_USES_V4L2_FH, &vfd->flags) ? fh : NULL;
if (vfh && vfh->ctrl_handler)
return v4l2_querymenu(vfh->ctrl_handler, p);
@@ -1518,7 +1518,7 @@ static int v4l_g_ctrl(const struct v4l2_ioctl_ops *ops,
{
struct video_device *vfd = video_devdata(file);
struct v4l2_control *p = arg;
- struct v4l2_fh *vfh = fh;
+ struct v4l2_fh *vfh = test_bit(V4L2_FL_USES_V4L2_FH, &vfd->flags) ? fh : NULL;
struct v4l2_ext_controls ctrls;
struct v4l2_ext_control ctrl;
@@ -1551,7 +1551,7 @@ static int v4l_s_ctrl(const struct v4l2_ioctl_ops *ops,
{
struct video_device *vfd = video_devdata(file);
struct v4l2_control *p = arg;
- struct v4l2_fh *vfh = fh;
+ struct v4l2_fh *vfh = test_bit(V4L2_FL_USES_V4L2_FH, &vfd->flags) ? fh : NULL;
struct v4l2_ext_controls ctrls;
struct v4l2_ext_control ctrl;
@@ -1579,7 +1579,7 @@ static int v4l_g_ext_ctrls(const struct v4l2_ioctl_ops *ops,
{
struct video_device *vfd = video_devdata(file);
struct v4l2_ext_controls *p = arg;
- struct v4l2_fh *vfh = fh;
+ struct v4l2_fh *vfh = test_bit(V4L2_FL_USES_V4L2_FH, &vfd->flags) ? fh : NULL;
p->error_idx = p->count;
if (vfh && vfh->ctrl_handler)
@@ -1597,7 +1597,7 @@ static int v4l_s_ext_ctrls(const struct v4l2_ioctl_ops *ops,
{
struct video_device *vfd = video_devdata(file);
struct v4l2_ext_controls *p = arg;
- struct v4l2_fh *vfh = fh;
+ struct v4l2_fh *vfh = test_bit(V4L2_FL_USES_V4L2_FH, &vfd->flags) ? fh : NULL;
p->error_idx = p->count;
if (vfh && vfh->ctrl_handler)
@@ -1615,7 +1615,7 @@ static int v4l_try_ext_ctrls(const struct v4l2_ioctl_ops *ops,
{
struct video_device *vfd = video_devdata(file);
struct v4l2_ext_controls *p = arg;
- struct v4l2_fh *vfh = fh;
+ struct v4l2_fh *vfh = test_bit(V4L2_FL_USES_V4L2_FH, &vfd->flags) ? fh : NULL;
p->error_idx = p->count;
if (vfh && vfh->ctrl_handler)
Regards,
Hans
> Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
> ---
> drivers/media/video/v4l2-ioctl.c | 21 ++++++++++++++-------
> 1 file changed, 14 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/media/video/v4l2-ioctl.c b/drivers/media/video/v4l2-ioctl.c
> index 70e0efb..3c498b2 100644
> --- a/drivers/media/video/v4l2-ioctl.c
> +++ b/drivers/media/video/v4l2-ioctl.c
> @@ -1488,7 +1488,8 @@ static int v4l_queryctrl(const struct v4l2_ioctl_ops *ops,
> struct v4l2_queryctrl *p = arg;
> struct v4l2_fh *vfh = fh;
>
> - if (vfh && vfh->ctrl_handler)
> + if (test_bit(V4L2_FL_USES_V4L2_FH, &vfd->flags) &&
> + vfh && vfh->ctrl_handler)
> return v4l2_queryctrl(vfh->ctrl_handler, p);
> if (vfd->ctrl_handler)
> return v4l2_queryctrl(vfd->ctrl_handler, p);
> @@ -1504,7 +1505,8 @@ static int v4l_querymenu(const struct v4l2_ioctl_ops *ops,
> struct v4l2_querymenu *p = arg;
> struct v4l2_fh *vfh = fh;
>
> - if (vfh && vfh->ctrl_handler)
> + if (test_bit(V4L2_FL_USES_V4L2_FH, &vfd->flags) &&
> + vfh && vfh->ctrl_handler)
> return v4l2_querymenu(vfh->ctrl_handler, p);
> if (vfd->ctrl_handler)
> return v4l2_querymenu(vfd->ctrl_handler, p);
> @@ -1522,7 +1524,8 @@ static int v4l_g_ctrl(const struct v4l2_ioctl_ops *ops,
> struct v4l2_ext_controls ctrls;
> struct v4l2_ext_control ctrl;
>
> - if (vfh && vfh->ctrl_handler)
> + if (test_bit(V4L2_FL_USES_V4L2_FH, &vfd->flags) &&
> + vfh && vfh->ctrl_handler)
> return v4l2_g_ctrl(vfh->ctrl_handler, p);
> if (vfd->ctrl_handler)
> return v4l2_g_ctrl(vfd->ctrl_handler, p);
> @@ -1555,7 +1558,8 @@ static int v4l_s_ctrl(const struct v4l2_ioctl_ops *ops,
> struct v4l2_ext_controls ctrls;
> struct v4l2_ext_control ctrl;
>
> - if (vfh && vfh->ctrl_handler)
> + if (test_bit(V4L2_FL_USES_V4L2_FH, &vfd->flags) &&
> + vfh && vfh->ctrl_handler)
> return v4l2_s_ctrl(vfh, vfh->ctrl_handler, p);
> if (vfd->ctrl_handler)
> return v4l2_s_ctrl(NULL, vfd->ctrl_handler, p);
> @@ -1582,7 +1586,8 @@ static int v4l_g_ext_ctrls(const struct v4l2_ioctl_ops *ops,
> struct v4l2_fh *vfh = fh;
>
> p->error_idx = p->count;
> - if (vfh && vfh->ctrl_handler)
> + if (test_bit(V4L2_FL_USES_V4L2_FH, &vfd->flags) &&
> + vfh && vfh->ctrl_handler)
> return v4l2_g_ext_ctrls(vfh->ctrl_handler, p);
> if (vfd->ctrl_handler)
> return v4l2_g_ext_ctrls(vfd->ctrl_handler, p);
> @@ -1600,7 +1605,8 @@ static int v4l_s_ext_ctrls(const struct v4l2_ioctl_ops *ops,
> struct v4l2_fh *vfh = fh;
>
> p->error_idx = p->count;
> - if (vfh && vfh->ctrl_handler)
> + if (test_bit(V4L2_FL_USES_V4L2_FH, &vfd->flags) &&
> + vfh && vfh->ctrl_handler)
> return v4l2_s_ext_ctrls(vfh, vfh->ctrl_handler, p);
> if (vfd->ctrl_handler)
> return v4l2_s_ext_ctrls(NULL, vfd->ctrl_handler, p);
> @@ -1618,7 +1624,8 @@ static int v4l_try_ext_ctrls(const struct v4l2_ioctl_ops *ops,
> struct v4l2_fh *vfh = fh;
>
> p->error_idx = p->count;
> - if (vfh && vfh->ctrl_handler)
> + if (test_bit(V4L2_FL_USES_V4L2_FH, &vfd->flags) &&
> + vfh && vfh->ctrl_handler)
> return v4l2_try_ext_ctrls(vfh->ctrl_handler, p);
> if (vfd->ctrl_handler)
> return v4l2_try_ext_ctrls(vfd->ctrl_handler, p);
>
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