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).
I'll send out a different patch that will cover the potential
coverityscan problem throughout the end of the week.
Best regards,
Daniel Scheller
--
https://github.com/herrnst
