Hi Richard, On 29 May 2012 17:02, Torne (Richard Coles) <torne@xxxxxxxxxx> wrote: > From: "Torne (Richard Coles)" <torne@xxxxxxxxxx> > > MMC CSD info can specify very large, ridiculous timeouts, big enough to > overflow timeout_ns on 32-bit machines. This can result in the card > timing out on every operation because the wrapped timeout value is far > too small. > > Fix the overflow by capping the result at 2 seconds. Cards specifying > longer timeouts are almost certainly insane, and host controllers > generally cannot support timeouts that long in any case. > > 2 seconds should be plenty of time for any card to actually function; > the timeout calculation code is already using 1 second as a "worst case" > timeout for cards running in SPI mode. > > Signed-off-by: Torne (Richard Coles) <torne@xxxxxxxxxx> > --- > drivers/mmc/core/core.c | 11 ++++++++++- > 1 files changed, 10 insertions(+), 1 deletions(-) > > diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c > index 0b6141d..3b4a9fc 100644 > --- a/drivers/mmc/core/core.c > +++ b/drivers/mmc/core/core.c > @@ -512,7 +512,16 @@ void mmc_set_data_timeout(struct mmc_data *data, const struct mmc_card *card) > if (data->flags & MMC_DATA_WRITE) > mult <<= card->csd.r2w_factor; > > - data->timeout_ns = card->csd.tacc_ns * mult; > + /* > + * The timeout in nanoseconds may overflow with some cards. Cap it at > + * two seconds both to avoid the overflow and also because host > + * controllers cannot generally generate timeouts that long anyway. > + */ > + if (card->csd.tacc_ns <= (2 * NSEC_PER_SEC) / mult) > + data->timeout_ns = card->csd.tacc_ns * mult; > + else > + data->timeout_ns = 2 * NSEC_PER_SEC; > + The above looks OK to me, although if doing this for tacc_ns we might want to do this for tacc_clks as well. Could we include that is this patch as well? > data->timeout_clks = card->csd.tacc_clks * mult; > > /* > -- > 1.7.7.3 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-mmc" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html Kind regards Ulf Hansson -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
