On Thu, Jun 7, 2012 at 6:52 AM, Theodore Ts'o <tytso@xxxxxxx> wrote: > Ext3 filesystems that are converted to use as many ext4 file system > features as possible will enable uninit_bg to speed up e2fsck times. > These file systems will have a native ext3 layout of inode tables and > block allocation bitmaps (as opposed to ext4's flex_bg layout). > Unfortunately, in these cases, when first allocating a block in an > uninitialized block group, ext4 would incorrectly calculate the number > of free blocks in that block group, and then errorneously report that > the file system was corrupt: > > EXT4-fs error (device vdd): ext4_mb_generate_buddy:741: group 30, 32254 clusters in bitmap, 32258 in gd > > This problem can be reproduced via: > > mke2fs -q -t ext4 -O ^flex_bg /dev/vdd 5g > mount -t ext4 /dev/vdd /mnt > fallocate -l 4600m /mnt/test > > The problem was caused by a bone headed mistake in the check to see if a > particular metadata block was part of the block group. > > Many thanks to Kees Cook for finding and bisecting the buggy commit > which introduced this bug (commit fd034a84e1, present since v3.2). > > Reported-by: Sander Eikelenboom <linux@xxxxxxxxxxxxxx> > Reported-by: Kees Cook <keescook@xxxxxxxxxxxx> > Signed-off-by: "Theodore Ts'o" <tytso@xxxxxxx> > Cc: stable@xxxxxxxxxx > Cc: Sander Eikelenboom <linux@xxxxxxxxxxxxxx> > Cc: Kees Cook <keescook@xxxxxxxxxxxx> Tested-by: Kees Cook <keescook@xxxxxxxxxxxx> Thanks! I can confirm that this fixes it. -Kees -- Kees Cook Chrome OS Security -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
