https://bugzilla.kernel.org/show_bug.cgi?id=211971 Bug ID: 211971 Summary: Incorrect fix by e2fsck for blocks_count corruption Product: File System Version: 2.5 Kernel Version: Linux 5.4.0-65-generic Hardware: x86-64 OS: Linux Tree: Mainline Status: NEW Severity: normal Priority: P1 Component: ext4 Assignee: fs_ext4@xxxxxxxxxxxxxxxxxxxx Reporter: tmahmud@xxxxxxxxxxx Regression: No Created attachment 295497 --> https://bugzilla.kernel.org/attachment.cgi?id=295497&action=edit log files from mke2fs, dumpe2fs and e2fsck For an ext4 file system image with only one superblock, if the blocks_count field in superblock is corrupted, e2fsck fixed it incorrectly. In the fixed image, the corrupted blocks_count is unchanged and other fields (e.g., free blocks count) are changed accordingly. This issue also occurs in images with multiple superblocks too. For example, For an ext4 image with primary and backup superblock (backup superblocks are not located in default locations, e.g., it is located on 513rd block), if the blocks_count field in superblock is corrupted, e2fsck fixed it incorrectly. In the fixed image, the corrupted blocks_count is unchanged and other fields (e.g., free blocks count) are changed accordingly. e2fsprogs_version_used: e2fsprogs 1.45.6 (20-Mar-2020) The commands that I ran to recreate the scenario are: For image with only one superblock: dd if=/dev/zero bs=1024 count=8193 of=/home/hdd/image mke2fs -b 1024 image 8193 debugfs -w image debugfs: ssv blocks_count 4000 debugfs: q e2fsck -yf image e2fsck -yf image # e2fsck fixes the blocks_count corruption in correctly # In the clean image the blocks_count was 8193, in the fixed image the blocks_count is 4000 #The second run of e2fsck is consistent with the first run, it doesn't fix anything, but blocks_count is still 4000 # Expected that e2fsck would fix the blocks count corruption instead of changing other fields (e.g.,free blocks_count) For image with multiple superblocks: dd if=/dev/zero bs=1024 count=8193 of=/home/hdd/image1 mke2fs -b 1024 -g 512 image1 8193 debugfs -w image1 debugfs: ssv blocks_count 4000 debugfs: q e2fsck -yf image1 e2fsck -yf image1 # e2fsck fixes the blocks_count corruption in correctly # In the clean image the blocks_count was 8193, in the fixed image the blocks_count is 4000 # The second run of e2fsck is consistent with the first run, it doesn't fix anything, but blocks_count is still 4000 #There were 16 block groups in the clean image, but there are only 7 block groups in the fixed image # Expected that e2fsck would fix the blocks count corruption instead of changing other fields (e.g.,free blocks_count) and removing the block groups. I attached the images and also the logs from mke2fs, dumpe2fs and e2fsck. -- You may reply to this email to add a comment. You are receiving this mail because: You are watching the assignee of the bug.
