Em Fri, 18 Oct 2024 08:13:01 +0200
Hans Verkuil <hverkuil@xxxxxxxxx> escreveu:
> On 18/10/2024 07:53, Mauro Carvalho Chehab wrote:
> > As detected by Coverity, the error check logic at get_ctrl() is
> > broken: if ptr_to_user() fails to fill a control due to an error,
> > no errors are returned and v4l2_g_ctrl() returns success on a
> > failed operation, which may cause applications to fail.
> >
> > Add an error check at get_ctrl() and ensure that it will
> > be returned to userspace without filling the control value if
> > get_ctrl() fails.
> >
> > Fixes: 71c689dc2e73 ("media: v4l2-ctrls: split up into four source files")
> > Cc: stable@xxxxxxxxxxxxxxx
> > Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@xxxxxxxxxx>
> > ---
> > drivers/media/v4l2-core/v4l2-ctrls-api.c | 16 +++++++++++-----
> > 1 file changed, 11 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/media/v4l2-core/v4l2-ctrls-api.c b/drivers/media/v4l2-core/v4l2-ctrls-api.c
> > index e5a364efd5e6..a0de7eeaf085 100644
> > --- a/drivers/media/v4l2-core/v4l2-ctrls-api.c
> > +++ b/drivers/media/v4l2-core/v4l2-ctrls-api.c
> > @@ -753,9 +753,10 @@ static int get_ctrl(struct v4l2_ctrl *ctrl, struct v4l2_ext_control *c)
> > for (i = 0; i < master->ncontrols; i++)
> > cur_to_new(master->cluster[i]);
> > ret = call_op(master, g_volatile_ctrl);
> > - new_to_user(c, ctrl);
> > + if (!ret)
> > + ret = new_to_user(c, ctrl);
> > } else {
> > - cur_to_user(c, ctrl);
> > + ret = cur_to_user(c, ctrl);
> > }
> > v4l2_ctrl_unlock(master);
> > return ret;
> > @@ -770,7 +771,10 @@ int v4l2_g_ctrl(struct v4l2_ctrl_handler *hdl, struct v4l2_control *control)
> > if (!ctrl || !ctrl->is_int)
> > return -EINVAL;
> > ret = get_ctrl(ctrl, &c);
> > - control->value = c.value;
> > +
> > + if (!ret)
> > + control->value = c.value;
> > +
> > return ret;
> > }
> > EXPORT_SYMBOL(v4l2_g_ctrl);
> > @@ -811,10 +815,12 @@ static int set_ctrl_lock(struct v4l2_fh *fh, struct v4l2_ctrl *ctrl,
> > int ret;
> >
> > v4l2_ctrl_lock(ctrl);
> > - user_to_new(c, ctrl);
> > + ret = user_to_new(c, ctrl);
> > + if (ret)
> > + return ret;
>
> A lock was taken above and that isn't unlocked here.
>
> It is better to write this as:
>
> if (!ret)
> ret = set_ctrl(fh, ctrl, 0);
>
> > ret = set_ctrl(fh, ctrl, 0);
> > if (!ret)
> > - cur_to_user(c, ctrl);
> > + ret = cur_to_user(c, ctrl);
> > v4l2_ctrl_unlock(ctrl);
> > return ret;
> > }
True. See below.
Thanks,
Mauro
-
[PATCH v3] media: v4l2-ctrls-api: fix error handling for v4l2_g_ctrl()
As detected by Coverity, the error check logic at get_ctrl() is
broken: if ptr_to_user() fails to fill a control due to an error,
no errors are returned and v4l2_g_ctrl() returns success on a
failed operation, which may cause applications to fail.
Add an error check at get_ctrl() and ensure that it will
be returned to userspace without filling the control value if
get_ctrl() fails.
Fixes: 71c689dc2e73 ("media: v4l2-ctrls: split up into four source files")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@xxxxxxxxxx>
---
drivers/media/v4l2-core/v4l2-ctrls-api.c | 17 +++++++++++------
1 file changed, 11 insertions(+), 6 deletions(-)
diff --git a/drivers/media/v4l2-core/v4l2-ctrls-api.c b/drivers/media/v4l2-core/v4l2-ctrls-api.c
index e5a364efd5e6..95a2202879d8 100644
--- a/drivers/media/v4l2-core/v4l2-ctrls-api.c
+++ b/drivers/media/v4l2-core/v4l2-ctrls-api.c
@@ -753,9 +753,10 @@ static int get_ctrl(struct v4l2_ctrl *ctrl, struct v4l2_ext_control *c)
for (i = 0; i < master->ncontrols; i++)
cur_to_new(master->cluster[i]);
ret = call_op(master, g_volatile_ctrl);
- new_to_user(c, ctrl);
+ if (!ret)
+ ret = new_to_user(c, ctrl);
} else {
- cur_to_user(c, ctrl);
+ ret = cur_to_user(c, ctrl);
}
v4l2_ctrl_unlock(master);
return ret;
@@ -770,7 +771,10 @@ int v4l2_g_ctrl(struct v4l2_ctrl_handler *hdl, struct v4l2_control *control)
if (!ctrl || !ctrl->is_int)
return -EINVAL;
ret = get_ctrl(ctrl, &c);
- control->value = c.value;
+
+ if (!ret)
+ control->value = c.value;
+
return ret;
}
EXPORT_SYMBOL(v4l2_g_ctrl);
@@ -811,10 +815,11 @@ static int set_ctrl_lock(struct v4l2_fh *fh, struct v4l2_ctrl *ctrl,
int ret;
v4l2_ctrl_lock(ctrl);
- user_to_new(c, ctrl);
- ret = set_ctrl(fh, ctrl, 0);
+ ret = user_to_new(c, ctrl);
+ if (!ret)
+ ret = set_ctrl(fh, ctrl, 0);
if (!ret)
- cur_to_user(c, ctrl);
+ ret = cur_to_user(c, ctrl);
v4l2_ctrl_unlock(ctrl);
return ret;
}
--
2.47.0
