If the CSD register contains a reserved value (4 - 7) in bits 0:2 of the TRAN_SPEED field, a buffer overrun occurs. Resize the mapping table.
According to the original report https://lore.kernel.org/u-boot/20180826231332.2491-11-erosca@de.adit-jv.com/ reserved values have been observed resulting in a buffer overrun.
Reported-by: Eugeniu Rosca erosca@de.adit-jv.com Fixes: 272cc70b211e ("Add MMC Framework") Signed-off-by: Heinrich Schuchardt heinrich.schuchardt@canonical.com --- drivers/mmc/mmc.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c index d96db7a0f8..00f4964aae 100644 --- a/drivers/mmc/mmc.c +++ b/drivers/mmc/mmc.c @@ -1570,13 +1570,20 @@ static int sd_read_ssr(struct mmc *mmc) return 0; } #endif -/* frequency bases */ -/* divided by 10 to be nice to platforms without floating point */ +/* + * TRAN_SPEED bits 0:2 encode the frequency unit: + * 0 = 100KHz, 1 = 1MHz, 2 = 10MHz, 3 = 100MHz, values 4 - 7 are reserved. + * The values in fbase[] are divided by 10 to avoid floats in multiplier[]. + */ static const int fbase[] = { 10000, 100000, 1000000, 10000000, + 0, /* reserved */ + 0, /* reserved */ + 0, /* reserved */ + 0, /* reserved */ };
/* Multiplier values for TRAN_SPEED. Multiplied by 10 to be nice @@ -2560,6 +2567,8 @@ static int mmc_startup(struct mmc *mmc) mult = multipliers[((cmd.response[0] >> 3) & 0xf)];
mmc->legacy_speed = freq * mult; + if (!mmc->legacy_speed) + log_debug("TRAN_SPEED: reserved value"); mmc_select_mode(mmc, MMC_LEGACY);
mmc->dsr_imp = ((cmd.response[1] >> 12) & 0x1);