Dear Przemyslaw Marczak, > Hi Marek, > > On 10/17/2013 07:41 PM, Marek Vasut wrote: > > Dear Przemyslaw Marczak, > > > >> Before this change ums disk capacity was miscalculated because > >> of integer overflow. > >> > >> Signed-off-by: Przemyslaw Marczak <p.marc...@samsung.com> > >> Cc: Marek Vasut <ma...@denx.de> > >> --- > >> > >> board/samsung/common/ums.c | 16 ++++++++++++---- > >> 1 file changed, 12 insertions(+), 4 deletions(-) > >> > >> diff --git a/board/samsung/common/ums.c b/board/samsung/common/ums.c > >> index 1f28590..6c4e6c4 100644 > >> --- a/board/samsung/common/ums.c > >> +++ b/board/samsung/common/ums.c > >> @@ -37,11 +37,19 @@ static int ums_write_sector(struct ums *ums_dev, > >> > >> static void ums_get_capacity(struct ums *ums_dev, long long int > >> *capacity) { > >> > >> - long long int tmp_capacity; > >> + int64_t mmc_capacity = (int64_t)ums_dev->mmc->capacity; > > > > Why are these casts here? > > > >> + int64_t ums_capacity = (int64_t)ums_dev->part_size * SECTOR_SIZE; > >> + int64_t ums_offset = (int64_t)ums_dev->offset * SECTOR_SIZE; > > > > And here all around? And why are these values signed, can there ever be > > negative value in them? > > I tried to fix it without changes in ums driver because it works fine. > Of course capacity can't be a negative value. > > When we set some offset and some part size we have an integer overflow > > at this line, just before cast to long long int: > >> - tmp_capacity = (long long int)((ums_dev->offset + ums_dev->part_size) > >> - * SECTOR_SIZE); > >> - *capacity = ums_dev->mmc->capacity - tmp_capacity; > > In the best case of overflow - ums partition capacity will have the same > value as mmc cap, but if offset was set, then the partition size will be > exceeded. > > >> + if (ums_capacity && ((ums_capacity + ums_offset) < mmc_capacity)) > >> + *capacity = ums_capacity; > >> + else > >> + *capacity = mmc_capacity - ums_offset; > > > > Urgh, what exactly does this code achieve again? > > This code above avoids situation when tmp_capacity value is bigger than > real mmc capacity. I don't check next the offset but this is also the > reason why I put printf here. I assume that developer should know how to > define UMS_START_BLOCK and UMS_PART_SIZE if no, some information will be > printed. > > >> + printf("UMS: partition capacity: %#llx blocks\n" > >> + "UMS: partition start block: %#x\n", > >> + *capacity / SECTOR_SIZE, > >> + ums_dev->offset); > >> > >> } > >> > >> static struct ums ums_dev = { > > > > Best regards, > > Marek Vasut > > In summary I will change signed variables to unsigned here and few in > the ums gadget driver. > Moreover now I think that it will be better to replace part_size from > the struct ums_dev with part_blk_num and compute its value at ums_init > function. And then pointer to ums_get_capacity is not needed in ums > structure. > > What do you think about this?
I think the first screaming thing here is ... why is this all multiplied by SECTOR_SIZE before doing the comparisons and stuffs ? You can do that later (that does mean do it later, yes). Try this: u64 mmc_cap = ums_dev->mmc->capacity / SECTOR_SIZE; u64 ums_start = ums_dev->offset; u64 ums_end = ums_start + ums_dev->part_size; /* Start past MMC size. */ if (ums_start >= mmc_cap) return -EINVAL; /* End past MMC size. */ if (ums_end > mmc_cap) { puts("UMS region larger than MMC device, capping\n"); ums_end = mmc_cap; } *capacity = (ums_end - ums_start) * SECTOR_SIZE; Does this work? You'd need to add debug. _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot