Re: [PATCH v2] ubi: gluebi: Fix NULL pointer dereference caused by ftl notifier

Richard Weinberger
2024-06-17T18:09:25Z

----- Ursprüngliche Mail -----
> Von: "Gagan Sidhu" <broly@mac.com>
> https://github.com/torvalds/linux/blob/master/drivers/mtd/ubi/gluebi.c#L297
>
> it seems the GLUEBI is setting the mtd to MTD_UBIVOLUME
>
> https://github.com/torvalds/linux/blob/master/drivers/mtd/ubi/block.c
>
> where this doesn’t even have the text “mtd” anywhere.
>
> but the boot partition is always the ubiblock device.
>
> so is gluebi taking the same volume and adding the MTD_UBIVOLUME label or
> something?

Yes, GLUEBI emulates a MTD on top of an UBI volume.
It sets the MTD device type to MTD_UBIVOLUME.

>>
>> [ 5.462504] auto-attach mtd7
>> [ 5.462525] ubi0: default fastmap pool size: 15
>> [ 5.477309] ubi0: default fastmap WL pool size: 7
>> [ 5.486683] ubi0: attaching mtd7
>> [ 5.811240] UBI: EOF marker found, PEBs from 273 will be erased
>> [ 5.811299] ubi0: scanning is finished
>> [ 5.874546] gluebi (pid 1): gluebi_resized: got update notification for
>> unknown UBI device 0 volume 1
>> [ 5.892927] ubi0: volume 1 ("rootfs_data") re-sized from 9 to 28 LEBs
>> [ 5.906683] ubi0: attached mtd7 (name "ubi", size 40 MiB)
>> [ 5.917446] ubi0: PEB size: 131072 bytes (128 KiB), LEB size: 126976 bytes
>> [ 5.931132] ubi0: min./max. I/O unit sizes: 2048/2048, sub-page size 2048
>> [ 5.944654] ubi0: VID header offset: 2048 (aligned 2048), data offset: 4096
>> [ 5.958513] ubi0: good PEBs: 320, bad PEBs: 0, corrupted PEBs: 0
>> [ 5.970472] ubi0: user volume: 2, internal volumes: 1, max. volumes count:
>> 128
>> [ 5.984859] ubi0: max/mean erase counter: 1/0, WL threshold: 4096, image
>> sequence number: 1613475955
>> [ 6.003045] ubi0: available PEBs: 0, total reserved PEBs: 320, PEBs reserved
>> for bad PEB handling: 15
>> [ 6.021426] rootfs: parsing partitions cmdlinepart
>> [ 6.021444] ubi0: background thread "ubi_bgt0d" started, PID 97
>> [ 6.043694] rootfs: got parser (null)
>> [ 6.051426] mtd: device 12 (rootfs) set to be root filesystem

AFAICT, this log line is not part of the mainline kernel.

>> [ 6.062891] rootfs_data: parsing partitions cmdlinepart
>> [ 6.073669] rootfs_data: got parser (null)
>> [ 6.211240] block ubiblock0_0: created from ubi0:0(rootfs)
>> [ 6.259545] rtc-pcf8563 0-0051: hctosys: unable to read the hardware clock
>> [ 6.282125] VFS: Cannot open root device "(null)" or unknown-block(31,12):
>> error -6
>> [ 6.297406] Please append a correct "root=" boot option; here are the
>> available partitions:
>> [ 6.314054] 1f00 512 mtdblock0
>> [ 6.314060] (driver?)
>> [ 6.327077] 1f01 256 mtdblock1
>> [ 6.327081] (driver?)
>> [ 6.340101] 1f02 256 mtdblock2
>> [ 6.340105] (driver?)
>> [ 6.353124] 1f03 256 mtdblock3
>> [ 6.353129] (driver?)
>> [ 6.366153] 1f04 45056 mtdblock4
>> [ 6.366158] (driver?)
>> [ 6.379175] 1f05 40572 mtdblock5
>> [ 6.379179] (driver?)
>> [ 6.392217] 1f06 4096 mtdblock6
>> [ 6.392222] (driver?)
>> [ 6.405240] 1f07 40960 mtdblock7
>> [ 6.405244] (driver?)
>> [ 6.418272] 1f08 32768 mtdblock8
>> [ 6.418277] (driver?)
>> [ 6.431296] 1f09 40960 mtdblock9
>> [ 6.431300] (driver?)
>> [ 6.444324] 1f0a 6144 mtdblock10
>> [ 6.444328] (driver?)
>> [ 6.457518] 1f0b 4608 mtdblock11
>> [ 6.457523] (driver?)
>> [ 6.470720] fe00 33604 ubiblock0_0
>> [ 6.470724] (driver?)
>> [ 6.484090] Kernel panic - not syncing: VFS: Unable to mount root fs on
>> unknown-block(31,12)

(31, 12) would be mtdblock12.
How does your kernel know that mtdblock12 shall be the rootfs?

I have a hard time understanding your current setup.

Thanks,
//richard