linux-kernel - Re: [PATCH v2 3/3] ext4: avoid overlapping preallocations due to overflow

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

Date:   Tue, 25 Jul 2023 23:00:43 +0530
From:   Ritesh Harjani (IBM) <ritesh.list@...il.com>
To:     Baokun Li <libaokun1@...wei.com>, linux-ext4@...r.kernel.org
Cc:     tytso@....edu, adilger.kernel@...ger.ca, jack@...e.cz,
        ojaswin@...ux.ibm.com, linux-kernel@...r.kernel.org,
        yi.zhang@...wei.com, yangerkun@...wei.com, yukuai3@...wei.com,
        libaokun1@...wei.com
Subject: Re: [PATCH v2 3/3] ext4: avoid overlapping preallocations due to overflow

Baokun Li <libaokun1@...wei.com> writes:

> Let's say we want to allocate 2 blocks starting from 4294966386, after
> predicting the file size, start is aligned to 4294965248, len is changed
> to 2048, then end = start + size = 0x100000000. Since end is of
> type ext4_lblk_t, i.e. uint, end is truncated to 0.
>
> This causes (pa->pa_lstart >= end) to always hold when checking if the
> current extent to be allocated crosses already preallocated blocks, so the
> resulting ac_g_ex may cross already preallocated blocks. Hence we convert
> the end type to loff_t and use pa_logical_end() to avoid overflow.
>
> Signed-off-by: Baokun Li <libaokun1@...wei.com>
> ---
>  fs/ext4/mballoc.c | 21 ++++++++++-----------
>  1 file changed, 10 insertions(+), 11 deletions(-)

Looks good to me. Feel free to add:

Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@...il.com>

-ritesh