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SubjectRe: [PATCH V3] MMC: core: cap MMC card timeouts at UINT_MAX
On 01/06/12 16:20, Torne (Richard Coles) wrote:
> From: "Torne (Richard Coles)" <torne@google.com>
>
> MMC CSD info can specify very large, ridiculous timeouts, big enough to
> overflow timeout_ns. 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 UINT_MAX. Cards specifying
> longer timeouts are almost certainly insane, and host controllers
> generally cannot support timeouts that long in any case.
>
> Signed-off-by: Torne (Richard Coles) <torne@google.com>
> ---
> 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..74ec3d4 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
> + * UINT_MAX to avoid the overflow; host controllers cannot generally
> + * generate timeouts that long anyway.
> + */
> + if (card->csd.tacc_ns <= UINT_MAX / mult)
> + data->timeout_ns = card->csd.tacc_ns * mult;
> + else
> + data->timeout_ns = UINT_MAX;
> +
> data->timeout_clks = card->csd.tacc_clks * mult;
>
> /*

Acked-by: Adrian Hunter <adrian.hunter@intel.com>


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