linux-kernel - Re: + seq_read-info-message-about-buggy-next-functions.patch added to -mm tree

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] [day] [month] [year] [list]

Date:   Tue, 3 Mar 2020 08:36:57 +0300
From:   Vasily Averin <vvs@...tuozzo.com>
To:     Andrew Morton <akpm@...ux-foundation.org>, Qian Cai <cai@....pw>
Cc:     linux-kernel@...r.kernel.org, dave@...olabs.net,
        longman@...hat.com, manfred@...orfullife.com, mingo@...hat.com,
        mm-commits@...r.kernel.org, neilb@...e.com, oberpar@...ux.ibm.com,
        rostedt@...dmis.org, viro@...iv.linux.org.uk,
        netfilter-devel@...r.kernel.org,
        Pablo Neira Ayuso <pablo@...filter.org>
Subject: Re: + seq_read-info-message-about-buggy-next-functions.patch added to
 -mm tree



On 3/2/20 11:42 PM, Andrew Morton wrote:
> On Mon, 02 Mar 2020 14:31:48 -0500 Qian Cai <cai@....pw> wrote:
> 
>> On Mon, 2020-03-02 at 13:20 -0500, Qian Cai wrote:
>>> This patch spams the console like crazy while reading sysfs,
>>>
>>> # dmesg | grep 'buggy seq_file' | wc -l
>>> 4204
>>>
>>> [ 9505.321981] LTP: starting read_all_proc (read_all -d /proc -q -r 10)
>>> [ 9508.222934] buggy seq_file .next function xt_match_seq_next [x_tables] did
>>> not updated position index
>>> [ 9508.223319] buggy seq_file .next function xt_match_seq_next [x_tables] did
>>> not updated position index
>>> [ 9508.223654] buggy seq_file .next function xt_match_seq_next [x_tables] did
>>> not updated position index
>>> [ 9508.223994] buggy seq_file .next function xt_match_seq_next [x_tables] did
>>> not updated position index
>>> [ 9508.224337] buggy seq_file .next function xt_match_seq_next [x_tables] did
>>> not updated position index

It should be fixed by following patch-set submitted to Netfilter-Devel mailing list
[PATCH v2 0/4] netfilter: seq_file .next functions should increase position index
https://lore.kernel.org/netfilter-devel/497a82c1-7b6a-adf4-a4ce-df46fe436aae@virtuozzo.com/T/

>>>> --- a/fs/seq_file.c~seq_read-info-message-about-buggy-next-functions
>>>> +++ a/fs/seq_file.c
>>>> @@ -256,9 +256,12 @@ Fill:
>>>>  		loff_t pos = m->index;
>>>>  
>>>>  		p = m->op->next(m, p, &m->index);
>>>> -		if (pos == m->index)
>>>> -			/* Buggy ->next function */
>>>> +		if (pos == m->index) {
>>>> +			pr_info("buggy seq_file .next function %ps "
>>>> +				"did not updated position index\n",
>>>> +				m->op->next);
>>
>> This?
>>
>> s/pr_info/pr_info_ratelimited/
>>
> 
> Fair enough - I made that change.
>