[ Hi Hans,
This might not really be your bug, but I just respect you a lot and
so I always come to you with questions and for advice. -dan ]
Hello Hans Verkuil,
The patch 6680427791c9: "[media] mxb: fix audio handling" from Apr
30, 2012, leads to the following static checker warning:
drivers/media/pci/saa7146/mxb.c:196 tea6420_route()
warn: uncapped user index 'TEA6420_cd[idx]'
drivers/media/pci/saa7146/mxb.c
194 static inline void tea6420_route(struct mxb *mxb, int idx)
195 {
--> 196 v4l2_subdev_call(mxb->tea6420_1, audio, s_routing,
197 TEA6420_cd[idx][0].input, TEA6420_cd[idx][0].output, 0);
^^^
Index overflow. The TEA6420_cd[] array has MXB_AUDIOS + 1 (which is 7
altogether) elements.
198 v4l2_subdev_call(mxb->tea6420_2, audio, s_routing,
199 TEA6420_cd[idx][1].input, TEA6420_cd[idx][1].output, 0);
200 v4l2_subdev_call(mxb->tea6420_1, audio, s_routing,
201 TEA6420_line[idx][0].input, TEA6420_line[idx][0].output, 0);
202 v4l2_subdev_call(mxb->tea6420_2, audio, s_routing,
203 TEA6420_line[idx][1].input, TEA6420_line[idx][1].output, 0);
204 }
[ snip ]
650 static int vidioc_s_audio(struct file *file, void *fh, const struct v4l2_audio *a)
651 {
652 struct saa7146_dev *dev = ((struct saa7146_fh *)fh)->dev;
653 struct mxb *mxb = (struct mxb *)dev->ext_priv;
654
655 DEB_D("VIDIOC_S_AUDIO %d\n", a->index);
656 if (mxb_inputs[mxb->cur_input].audioset & (1 << a->index)) {
This a->index comes from the ioctl and it's a u32 so the shift can wrap.
The .audioset variable is always 0x3f. In other words BIT(6) is the
highest valid bit so we could add a check:
if (a->index > MXB_AUDIOS)
return;
657 if (mxb->cur_audinput != a->index) {
658 mxb->cur_audinput = a->index;
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Now here's the complication. We also use a->index as an index into the
mxb_inputs[] array which only has MXB_INPUTS (4) elements, so just
adding the limit would still lead to a different array out of bounds
later...
659 tea6420_route(mxb, a->index);
660 if (mxb->cur_audinput == 0)
661 mxb_update_audmode(mxb);
662 }
663 return 0;
664 }
665 return -EINVAL;
666 }
regards,
dan carpenter
