Re: [PATCH mtd-utils] libmtd: don't ignore "region index" parameter in mtd_regioninfo()

Brian Norris
2014-11-05T03:02:05Z

On Mon, Sep 15, 2014 at 10:48:21AM -0700, Brian Norris wrote:
> ioctl(MEMGETREGIONINFO) has one input parameter (regionindex) and three
> output parameters (info about the erase region). There are two problems
> in mtdinfo/libmtd here:
>
> 1. mtdinfo.c doesn't initialize its region_info_user struct, instead
> passing uninitialized data to mtd_regioninfo()
>
> 2. mtd_regioninfo() fails to utilize the 'regidx' parameter to fill out
> the regionindex parameter properly, so the garbage from mtdinfo.c is
> propagated to the ioctl()
>
> This means that mtdinfo will continuously probe the same (possibly
> out-of-range) erase region, instead of looping over the valid regions.
>
> Let's fix this in the mtd_regioninfo() helper, and at the same time,
> let's zero out the mtdinfo.c buffer, as an additional precaution to keep
> from using uninitialized data.
>
> Initial error report from Yang, when running "mtdinfo /dev/mtd0" on a
> Cavium 6100 board:
>
> root@CN61XX:~# mtdinfo /dev/mtd0
> mtd0
> Name: phys_mapped_flash
> Type: nor
> Eraseblock size: 65536 bytes, 64.0 KiB
> Amount of eraseblocks: 128 (8388608 bytes, 8.0 MiB)
> Minimum input/output unit size: 1 byte
> Sub-page size: 1 byte
> Additional erase regions: 0
> Character device major/minor: 90:0
> Bad blocks are allowed: false
> Device is writable: true
> libmtd: error!: MEMGETREGIONINFO ioctl failed for erase region 0
> error 22 (Invalid argument)
> Eraseblock region 0: info is unavailable
> libmtd: error!: MEMGETREGIONINFO ioctl failed for erase region 1
> error 22 (Invalid argument)
> Eraseblock region 1: info is unavailable
>
> Reported-by: Yang Wei <Wei.Yang@windriver.com>
> Signed-off-by: Brian Norris <computersforpeace@gmail.com>

Pushed to mtd-utils.git.

Brian