Messages in this thread | | | Subject | Re: [PATCH 1/3] quota: Check next/prev free block number after reading from quota file | From | Zhihao Cheng <> | Date | Thu, 22 Sep 2022 16:13:59 +0800 |
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在 2022/9/21 21:37, Jan Kara 写道: Hi Jan, > On Sat 20-08-22 19:05:12, Zhihao Cheng wrote: >> Following process: [...] >> >> Link: https://bugzilla.kernel.org/show_bug.cgi?id=216372 >> Fixes: 1da177e4c3f4152 ("Linux-2.6.12-rc2") > > It's better to just have: > > CC: stable@vger.kernel.org > > here. Fixes tag pointing to kernel release is not very useful. Will add in v2. > >> --- a/fs/quota/quota_tree.c >> +++ b/fs/quota/quota_tree.c >> @@ -71,6 +71,35 @@ static ssize_t write_blk(struct qtree_mem_dqinfo *info, uint blk, char *buf) >> return ret; >> } >> >> +static inline int do_check_range(struct super_block *sb, uint val, uint max_val) >> +{ >> + if (val >= max_val) { >> + quota_error(sb, "Getting block too big (%u >= %u)", >> + val, max_val); >> + return -EUCLEAN; >> + } >> + >> + return 0; >> +} > > I'd already provide min_val and the string for the message here as well (as > you do in patch 2). It is less churn in the next patch and free blocks > checking actually needs that as well. See below. > >> + >> +static int check_free_block(struct qtree_mem_dqinfo *info, >> + struct qt_disk_dqdbheader *dh) >> +{ >> + int err = 0; >> + uint nextblk, prevblk; >> + >> + nextblk = le32_to_cpu(dh->dqdh_next_free); >> + err = do_check_range(info->dqi_sb, nextblk, info->dqi_blocks); >> + if (err) >> + return err; >> + prevblk = le32_to_cpu(dh->dqdh_prev_free); >> + err = do_check_range(info->dqi_sb, prevblk, info->dqi_blocks); >> + if (err) >> + return err; > > The free block should actually be > QT_TREEOFF so I'd add the check to > do_check_range().
'dh->dqdh_next_free' may be updated when quota entry removed, 'dh->dqdh_next_free' can be used for next new quota entris. Before sending v2, I found 'dh->dqdh_next_free' and 'dh->dqdh_prev_free' can easily be zero in newly allocated blocks when continually creating files onwed by different users: find_free_dqentry get_free_dqblk write_blk(info, info->dqi_blocks, buf) // zero'd qt_disk_dqdbheader blk = info->dqi_blocks++ // allocate new one block info->dqi_free_entry = blk // will be used for new quota entries
find_free_dqentry if (info->dqi_free_entry) blk = info->dqi_free_entry read_blk(info, blk, buf) // dh->dqdh_next_free = dh->dqdh_prev_free = 0
I think it's normal when 'dh->dqdh_next_free' or 'dh->dqdh_prev_free' equals to 0. > > Also rather than having check_free_block(), I'd provide a helper function > like check_dquot_block_header() which will check only free blocks pointers > now and in later patches you can add other checks there. OK, will be updated in v2. > > Honza >
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