linux-ext4 - ext4 and dd of emmc

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:   Thu, 22 Oct 2020 10:46:18 -0700
From:   Radivoje Jovanovic <radivojejovanovic@...il.com>
To:     linux-ext4@...r.kernel.org
Subject: ext4 and dd of emmc

Hello,
I am creating empty  4GB ext4 partition on emmc with parted like this:
parted -s -a optimal /dev/emmcblk0 mkpart data ext4 1024 5120
mkfs.ext4 /dev/mmcblk0p7 (this is the partition that was created in
the previous step)

I do not mount this partition before I do dd of the emmc.
dd of the emmc is done like this:
dd if=/dev/emmcblk0 | gzip -c | dd of=./image.bin

after this I write back the emmc with the same binary file:
dd if=./image.bin | gunzip -c | dd of=. /dev/emmcblk0

now I boot the system and mount the partition from the emmc.

at the boot the kernel reports:
EXT4-fs (mmcblk0p7): warning: mounting fs with errors, running e2fsck
is recommended

after the system is fully booted I see errors such as:
EXT4-fs error (device mmcblk0p7): ext4_journal_check_start:61:
Detected aborted journal
Buffer I/O error on dev mmcblk0p7, logical block 0, lost sync page write
EXT4-fs (mmcblk0p7): I/O error while writing superblock

All other partitions on the system are ReadOnly so probably that is
why I do not see errors for them

I am running custom Yocto build on this.
the kernel is vanilla 5.4.57 with an additional pci driver we have.

Any idea why this is happening?

Thanks
Ogi