Hi Colin,
Am Tue, 8 May 2018 11:39:56 +0100
schrieb Colin Ian King <colin.king@xxxxxxxxxxxxx>:
> On 08/05/18 11:38, Daniel Scheller wrote:
> > Hi Colin,
> >
> > Am Tue, 8 May 2018 00:08:42 +0100
> > schrieb Colin King <colin.king@xxxxxxxxxxxxx>:
> >
> >> From: Colin Ian King <colin.king@xxxxxxxxxxxxx>
> >>
> >> In function stop there is a check to see if state->demod is a stopped
> >> value of 0xff, however, later on, array demod_in_use is indexed with
> >> this value causing an out-of-bounds write error. Avoid this by only
> >> writing to array demod_in_use if state->demod is not set to the stopped
> >> sentinal value for this specific corner case. Also, replace the magic
> >> value 0xff with DEMOD_STOPPED to make code more readable.
> >>
> >> Detected by CoverityScan, CID#1468550 ("Out-of-bounds write")
> >>
> >> Fixes: daeeb1319e6f ("media: ddbridge: initial support for MCI-based MaxSX8 cards")
> >> Signed-off-by: Colin Ian King <colin.king@xxxxxxxxxxxxx>
> >> ---
> >> drivers/media/pci/ddbridge/ddbridge-mci.c | 11 +++++++----
> >> 1 file changed, 7 insertions(+), 4 deletions(-)
> >>
> >> diff --git a/drivers/media/pci/ddbridge/ddbridge-mci.c b/drivers/media/pci/ddbridge/ddbridge-mci.c
> >> index a85ff3e6b919..1f5ed53c8d35 100644
> >> --- a/drivers/media/pci/ddbridge/ddbridge-mci.c
> >> +++ b/drivers/media/pci/ddbridge/ddbridge-mci.c
> >> @@ -20,6 +20,8 @@
> >> #include "ddbridge-io.h"
> >> #include "ddbridge-mci.h"
> >>
> >> +#define DEMOD_STOPPED (0xff)
> >> +
> >> static LIST_HEAD(mci_list);
> >>
> >> static const u32 MCLK = (1550000000 / 12);
> >> @@ -193,7 +195,7 @@ static int stop(struct dvb_frontend *fe)
> >> u32 input = state->tuner;
> >>
> >> memset(&cmd, 0, sizeof(cmd));
> >> - if (state->demod != 0xff) {
> >> + if (state->demod != DEMOD_STOPPED) {
> >> cmd.command = MCI_CMD_STOP;
> >> cmd.demod = state->demod;
> >> mci_cmd(state, &cmd, NULL);
> >> @@ -209,10 +211,11 @@ static int stop(struct dvb_frontend *fe)
> >> state->base->tuner_use_count[input]--;
> >> if (!state->base->tuner_use_count[input])
> >> mci_set_tuner(fe, input, 0);
> >> - state->base->demod_in_use[state->demod] = 0;
> >> + if (state->demod != DEMOD_STOPPED)
> >> + state->base->demod_in_use[state->demod] = 0;
> >> state->base->used_ldpc_bitrate[state->nr] = 0;
> >> - state->demod = 0xff;
> >> - state->base->assigned_demod[state->nr] = 0xff;
> >> + state->demod = DEMOD_STOPPED;
> >> + state->base->assigned_demod[state->nr] = DEMOD_STOPPED;
> >> state->base->iq_mode = 0;
> >> mutex_unlock(&state->base->tuner_lock);
> >> state->started = 0;
> >
> > Thanks for the patch, or - better - pointing this out. While it's
> > unlikely this will ever be an issue, I'm fine with changing the code
> > like that, but I'd prefer to change it a bit differently (ie.
> > DEMOD_STOPPED should be DEMOD_UNUSED, and I'd add defines for max.
> > tuners and use/compare against them).
>
> Sounds like a good idea.
>
> >
> > I'll send out a different patch that will cover the potential
> > coverityscan problem throughout the end of the week.
>
> Great. Thanks!
JFYI, patch sent as part of a few other fixes and up at linux-media
patchwork:
https://patchwork.linuxtv.org/patch/49403/
Best regards,
Daniel Scheller
--
https://github.com/herrnst
