linux-ext4 - [PATCH] ext4: Do not dec quota for reserved blocks on error paths

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 linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

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

Message-ID: <87633dcxhp.fsf@openvz.org>
Date:	Tue, 27 Apr 2010 08:47:46 +0400
From:	Dmitry Monakhov <dmonakhov@...nvz.org>
To:	linux-ext4@...r.kernel.org
Subject: [PATCH] ext4: Do not dec quota for reserved blocks on error paths

If we have failed some where inside ext4_get_blocks() internals we may
have allocated some new blocks, which was not yet claimed to quota.
We have to free such blocks, but without touching quota. Quota will
be updated later on exit from ext4_get_blocks().
There are two possible ways to understand what we have to skip quota update:
1) Caller pass corresponding flag to ext4_free_blocks()
2) check that free_blocks() was indirectly called by get_blocks() 
   (i.e EXT4_I(inode)->i_delalloc_reserved_flag is set)
Second is simpler, but may result in unpredictable consequences later.
So i've chosen the first one, because caller must know which blocks it
is freeing.

The bug happens on heavily loaded node, or with 227'th xfstestcase and
result in incorrect i_blocks (less than expected). So truncation for
that file result in i_blocks overflow.
Seems this was the last bug which was easily triggered by 227'th testcase.

Test hosts survived for 24hrs without complain. Tested configuration:
* ext3 over ext4driver with -odelalloc mount option
* ext4 with default mount opt

View attachment "0001-ext4-Do-not-drop-quota-for-reserved-blocks-on-error-.patch" of type "text/plain" (5637 bytes)