On Mon, Sep 19, 2016 at 03:31:54PM +0900, Jaehoon Chung wrote: > On 09/19/2016 02:53 AM, Tom Rini wrote: > > 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. > > I think cid doesn't need to change type.
I mean the coverity CID :) In the public coverity project it's 149300 > > > > >> --- > >> 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! > > Maybe not to move down to a u8..because it's displayed the real capacity for > storage. We could update those lines too? It's just that one case right there, yes? > And i wonder that coverity didn't report about the line 1294? It does, along with 1256. Thanks! -- Tom
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