On Tue, Sep 13, 2016 at 04:27:57PM +0800, Haibo Chen wrote: > Suspicious implicit sign extension exist. ext_csd[] is defined > as "u8", capacity is defined as u64, so u8 is promoted to signed > int first int the "|" expersion, then the sign extended to u64. > if the tmp sign value is largeer than 0x7fffffff, after the sign > extension, the upper bits of the result will all be 1. > Thanks to coverity <http://www.coverity.com> > > e.g. > u8 data_8; > u64 data_64; > > data_8 = 0x80; > data_64 = data_8 << 24; //0xffffffff80000000 > data_64 = ((u64)data_8) << 24; //0x80000000 > > Signed-off-by: Haibo Chen <haibo.c...@nxp.com>
Please add a 'Reported-by: Coverity' and you can include the CID if you like. > --- > drivers/mmc/mmc.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c > index 43ea0bb..c1d1dc6 100644 > --- a/drivers/mmc/mmc.c > +++ b/drivers/mmc/mmc.c > @@ -1176,10 +1176,10 @@ static int mmc_startup(struct mmc *mmc) > * ext_csd's capacity is valid if the value is more > * than 2GB > */ > - capacity = ext_csd[EXT_CSD_SEC_CNT] << 0 > - | ext_csd[EXT_CSD_SEC_CNT + 1] << 8 > - | ext_csd[EXT_CSD_SEC_CNT + 2] << 16 > - | ext_csd[EXT_CSD_SEC_CNT + 3] << 24; > + capacity = ((u64)ext_csd[EXT_CSD_SEC_CNT]) << 0 > + | ((u64)ext_csd[EXT_CSD_SEC_CNT + 1]) > << 8 > + | ((u64)ext_csd[EXT_CSD_SEC_CNT + 2]) > << 16 > + | ((u64)ext_csd[EXT_CSD_SEC_CNT + 3]) > << 24; > capacity *= MMC_MAX_BLOCK_LEN; > if ((capacity >> 20) > 2 * 1024) > mmc->capacity_user = capacity; Can't we just move capacity down to a u8 instead? Thanks! -- Tom
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