linux-kernel - Re: [PATCH v2 7/9] trace_uprobe/sdt: Fix multiple update of same reference counter

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]

Message-Id: <84c1e60f-8aad-a0ce-59af-4fcb3f77df94@linux.vnet.ibm.com>
Date:   Tue, 10 Apr 2018 13:49:12 +0530
From:   Ravi Bangoria <ravi.bangoria@...ux.vnet.ibm.com>
To:     Oleg Nesterov <oleg@...hat.com>
Cc:     mhiramat@...nel.org, peterz@...radead.org,
        srikar@...ux.vnet.ibm.com, rostedt@...dmis.org, acme@...nel.org,
        ananth@...ux.vnet.ibm.com, akpm@...ux-foundation.org,
        alexander.shishkin@...ux.intel.com, alexis.berlemont@...il.com,
        corbet@....net, dan.j.williams@...el.com, jolsa@...hat.com,
        kan.liang@...el.com, kjlx@...pleofstupid.com,
        kstewart@...uxfoundation.org, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        milian.wolff@...b.com, mingo@...hat.com, namhyung@...nel.org,
        naveen.n.rao@...ux.vnet.ibm.com, pc@...ibm.com, tglx@...utronix.de,
        yao.jin@...ux.intel.com, fengguang.wu@...el.com,
        jglisse@...hat.com,
        Ravi Bangoria <ravi.bangoria@...ux.vnet.ibm.com>
Subject: Re: [PATCH v2 7/9] trace_uprobe/sdt: Fix multiple update of same
 reference counter

Hi Oleg,

On 04/09/2018 06:59 PM, Oleg Nesterov wrote:
> On 04/04, Ravi Bangoria wrote:
>> +static void sdt_add_mm_list(struct trace_uprobe *tu, struct mm_struct *mm)
>> +{
>> +	struct mmu_notifier *mn;
>> +	struct sdt_mm_list *sml = kzalloc(sizeof(*sml), GFP_KERNEL);
>> +
>> +	if (!sml)
>> +		return;
>> +	sml->mm = mm;
>> +	list_add(&(sml->list), &(tu->sml.list));
>> +
>> +	/* Register mmu_notifier for this mm. */
>> +	mn = kzalloc(sizeof(*mn), GFP_KERNEL);
>> +	if (!mn)
>> +		return;
>> +
>> +	mn->ops = &sdt_mmu_notifier_ops;
>> +	__mmu_notifier_register(mn, mm);
>> +}
> and what if __mmu_notifier_register() fails simply because signal_pending() == T?
> see mm_take_all_locks().
>
> at first glance this all look suspicious and sub-optimal,

Yes. I should have added checks for failure cases.
Will fix them in v3.

Thanks for the review,
Ravi

>  but let me repeat that
> I didn't read this version yet.
>
> Oleg.
>