[U-Boot] [Bug & Question] ubifs does not understand ".." in file path ?

[Marek Vasut <marex@denx.de>]

On 07/13/2018 09:44 AM, Heiko Schocher wrote:
> Hello Masahiro,
> 
> Am 13.07.2018 um 06:44 schrieb Masahiro Yamada:
>> Hi.
>>
>>
>> I was playing around with the ditro-boot on NAND + UBI.
>>
>> I was hit by a problem when loading files from ubifs.
>>
>>
>> My 'extlinux.conf' script looks like this:
>>
>> ---------------------------------
>> menu title UniPhier Boot Options.
>>
>> timeout 5
>>
>> default UniPhier
>>
>> label UniPhier
>>        kernel ../Image
>>        initrd ../rootfs.cpio.gz
>>        fdtdir ..
>> ----------------------------------
>>
>>
>> As doc/README.distro says,
>> 'extlinux.conf' is generally located in 'extlinux' subdirectory.
>>
>> So, the paths to kernel, initrd, fdt usually contain '..'
>>
>> This totally works fine when loading files
>> from a FAT-formated MMC device.
>>
>> 'run bootcmd_mmc0' successfully boots Linus
>> in the disto-boot manner.
>>
>>
>>
>> However, 'run bootcmd_ubifs0' fails to boot.
>>
>>
>> => run bootcmd_ubifs0
>> ubi0: attaching mtd1
>> ubi0: scanning is finished
>> ubi0: attached mtd1 (name "mtd=1", size 1023 MiB)
>> ubi0: PEB size: 262144 bytes (256 KiB), LEB size: 253952 bytes
>> ubi0: min./max. I/O unit sizes: 4096/4096, sub-page size 4096
>> ubi0: VID header offset: 4096 (aligned 4096), data offset: 8192
>> ubi0: good PEBs: 4088, bad PEBs: 4, corrupted PEBs: 0
>> ubi0: user volume: 1, internal volumes: 1, max. volumes count: 128
>> ubi0: max/mean erase counter: 1/0, WL threshold: 4096, image sequence
>> number: 1407739552
>> ubi0: available PEBs: 0, total reserved PEBs: 4088, PEBs reserved for
>> bad PEB handling: 76
>> UBIFS (ubi0:0): UBIFS: mounted UBI device 0, volume 0, name "boot",
>> R/O mode
>> UBIFS (ubi0:0): LEB size: 253952 bytes (248 KiB), min./max. I/O unit
>> sizes: 4096 bytes/4096 bytes
>> UBIFS (ubi0:0): FS size: 1014284288 bytes (967 MiB, 3994 LEBs),
>> journal size 33521664 bytes (31 MiB, 132 LEBs)
>> UBIFS (ubi0:0): reserved for root: 4952683 bytes (4836 KiB)
>> UBIFS (ubi0:0): media format: w5/r0 (latest is w4/r0), UUID
>> cc8f68da-030d-408c-a91f-f8cc195a2946, small LPT model
>> Scanning ubi 0:...
>> Found /boot/extlinux/extlinux.conf
>> Retrieving file: /boot/extlinux/extlinux.conf
>> 148 bytes read in 1 ms (144.5 KiB/s)
>> UniPhier Boot Options.
>> 1:      UniPhier
>> Enter choice: 1:        UniPhier
>> Retrieving file: /boot/extlinux/../rootfs.cpio.gz
>> Skipping UniPhier for failure retrieving initrd
>> SCRIPT FAILED: continuing...
>>
>>
>>
>>
>> The boot log says
>> it succeeded in loading '/boot/extlinux/extlinux.conf'
>> but failed in loading '/boot/extlinux/../rootfs.cpio.gz'
>>
>>
>>
>> In my quick experiments,
>>
>> load '/boot/extlinux/extlinux.conf'            -> SUCCESS
>> load '/boot/extlinux/../rootfs.cpio.gz'        -> FAILURE
>> load '/boot/rootfs.cpio.gz'                    -> SUCCESS
>> load '/boot/extlinux/../Image'                 -> FAILURE
>> load '/boot/Image'                             -> SUCCESS
>> load '/boot/extlinux/../uniphier-ld20-ref.dtb' -> FAILURE
>> load '/boot/uniphier-ld20-ref.dtb'             -> SUCCESS
>>
>>
>>
>>  From the test results above,
>> my conclusion is loading a file path that contains '..' is not working.
>>
>>
>> Not sure where the root cause is.
>> Anybody who has insight about this?
> 
> No idea, need to try it, but may
> 
> fs/ubifs/ubifs.c ubifs_findfile() has a problem with ".." ?

CCing Richard, btw ubifs in U-Boot is completely broken.

-- 
Best regards,
Marek Vasut