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
| ||
|
Date: Thu, 13 Sep 2012 20:57:26 +0800 From: Zheng Liu <gnehzuil.liu@...il.com> To: Jan Kara <jack@...e.cz> Cc: Dmitry Monakhov <dmonakhov@...nvz.org>, linux-ext4@...r.kernel.org, tytso@....edu, wenqing.lz@...bao.com Subject: Re: [PATCH 6/7] ext4: endless truncate due to nonlocked dio readers V2 On Thu, Sep 13, 2012 at 02:07:36PM +0200, Jan Kara wrote: > Hello, > > On Thu 13-09-12 18:41:36, Zheng Liu wrote: > > Could you please provide more detailed workload to convince me? I > > am thinking about whether we really need to disable dioread_nolock > > feature in here. In our benchmarks, we don't see this problem. > I just did: > > # Create file > dd if=/dev/zero of=/mnt/file bs=1M count=30 > sync > # Start 10 DIO dio readers in parallel reading the file in a loop > for (( i = 0; i < 10; i++ )); do > while true; do > dd if=/mnt/file bs=4k iflag=direct of=/dev/null > done & > done > sleep 1 > > # Try to truncate the file - never finishes. > truncate -s 16 /mnt/file > > It is pretty easy to hit this. Besides being a DOS attack vector (but I > won't be too concerned about this - there are plenty of ways how local > process can screw you) I can easily imagine some application to get bitten > by this. Hi Jan, Thanks for your explanation, but in my desktop I cannot reproduce this problem. The size of `file' is 16. Am I missing something? Regards, Zheng -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Powered by blists - more mailing lists