Hi, Stephan noticed that the Format string of the debug message was not %lu - thats why i sent a PATCH v2. > Gesendet: Mittwoch, den 16.08.2023 um 12:20 Uhr > Von: "Jan Kara" <jack@xxxxxxx> > An: "Andreas Dilger" <adilger@xxxxxxxxx> > Cc: "Georg Ottinger" <g.ottinger@xxxxxx>, jack@xxxxxxxx, linux-ext4@xxxxxxxxxxxxxxx > Betreff: Re: [PATCH v1] ext2: fix datatype of block number in ext2_xattr_set2() > > Hello! > > On Tue 15-08-23 06:18:43, Andreas Dilger wrote: > > On Aug 15, 2023, at 04:04, Georg Ottinger <g.ottinger@xxxxxx> wrote: > > > I run a small server that uses external hard drives for backups. The > > > backup software I use uses ext2 filesystems with 4KiB block size and > > > the server is running SELinux and therefore relies on xattr. I recently > > > upgraded the hard drives from 4TB to 12TB models. I noticed that after > > > transferring some TBs I got a filesystem error "Freeing blocks not in > > > datazone - block = 18446744071529317386, count = 1" and the backup > > > process stopped. Trying to fix the fs with e2fsck resulted in a > > > completely corrupted fs. The error probably came from ext2_free_blocks(), > > > and because of the large number 18e19 this problem immediately looked > > > like some kind of integer overflow. Whereas the 4TB fs was about 1e9 > > > blocks, the new 12TB is about 3e9 blocks. So, searching the ext2 code, > > > I came across the line in fs/ext2/xattr.c:745 where ext2_new_block() > > > is called and the resulting block number is stored in the variable block > > > as an int datatype. If a block with a block number greater than > > > INT32_MAX is returned, this variable overflows and the call to > > > sb_getblk() at line fs/ext2/xattr.c:750 fails, then the call to > > > ext2_free_blocks() produces the error. > > > > It would be useful to also do a quick grep through the rest of the ext2 > > code to check for this bug in other places calling ext2_mew_block() and > > similar calls. > > I did actually check when merging the patch and all the other places are > storing returned block in ext2_fsblk_t. > > Honza > > -- > Jan Kara <jack@xxxxxxxx> > SUSE Labs, CR
