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Message-Id: <1338282140-11106-1-git-send-email-torne@google.com> Date: Tue, 29 May 2012 10:02:20 +0100 From: "Torne (Richard Coles)" <torne@...gle.com> To: cjb@...top.org Cc: linus.walleij@...aro.org, jh80.chung@...sung.com, linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org, ben@...adent.org.uk, "Torne (Richard Coles)" <torne@...gle.com> Subject: [PATCH] MMC: core: cap MMC card timeouts at 2 seconds. From: "Torne (Richard Coles)" <torne@...gle.com> 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@...gle.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..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; + data->timeout_clks = card->csd.tacc_clks * mult; /* -- 1.7.7.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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