linux-kernel - Re: [PATCH v4 4/7] powerpc/kprobes: Use safer string functions in kprobe_lookup

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:   Sun, 23 Apr 2017 17:09:34 +0000
From:   "Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>
To:     Masami Hiramatsu <mhiramat@...nel.org>,
        Michael Ellerman <mpe@...erman.id.au>, pc@...ibm.com
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        Ingo Molnar <mingo@...nel.org>
Subject: Re: [PATCH v4 4/7] powerpc/kprobes: Use safer string functions in
 kprobe_lookup_name()

Excerpts from Paul Clarke's message of April 21, 2017 19:22:
> Sent too soon.  The suggestions don't guarantee null termination.  Refined, below. (Sorry for the noise.)

Yeah, the string operations here are a bit of a minefield...

> 
> On 04/21/2017 08:33 AM, Paul Clarke wrote:
>> On 04/21/2017 07:33 AM, Naveen N. Rao wrote:
>>> Convert usage of strchr()/strncpy()/strncat() to
>>> strnchr()/memcpy()/strlcat() for simpler and safer string manipulation.
> 
>>> diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
>>> index 97b5eed1f76d..c73fb6e3b43f 100644
>>> --- a/arch/powerpc/kernel/kprobes.c
>>> +++ b/arch/powerpc/kernel/kprobes.c
>>> @@ -65,28 +65,27 @@ kprobe_opcode_t *kprobe_lookup_name(const char *name, unsigned int offset)
>>>  	char dot_name[MODULE_NAME_LEN + 1 + KSYM_NAME_LEN];
>>>  	const char *modsym;
>>>  	bool dot_appended = false;
>>> -	if ((modsym = strchr(name, ':')) != NULL) {
>>> +	if ((modsym = strnchr(name, ':', MODULE_NAME_LEN)) != NULL) {

... as I just realized this is an epic FAIL! ;/

I will take my time to redo this.

- Naveen