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Re: [PATCH v4 4/7] powerpc/kprobes: Use safer string functions in kprobe_lookup_name()

From "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>
Newsgroups linux.kernel
Subject Re: [PATCH v4 4/7] powerpc/kprobes: Use safer string functions in kprobe_lookup_name()
Date 2017-04-23 19:20 +0200
Message-ID <tztl0-2UP-5@gated-at.bofh.it> (permalink)
References <txXnc-3yQ-25@gated-at.bofh.it> <tyG0W-5O5-19@gated-at.bofh.it> <tyGWZ-6mH-1@gated-at.bofh.it> <tyHgl-6ts-1@gated-at.bofh.it>
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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

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Thread

[PATCH v3 3/7] kprobes: validate the symbol name length "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> - 2017-04-19 15:00 +0200
  Re: [PATCH v3 3/7] kprobes: validate the symbol name length Masami Hiramatsu <mhiramat@kernel.org> - 2017-04-19 17:40 +0200
    Re: [PATCH v3 3/7] kprobes: validate the symbol name length "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> - 2017-04-19 18:40 +0200
      Re: [PATCH v3 3/7] kprobes: validate the symbol name length Masami Hiramatsu <mhiramat@kernel.org> - 2017-04-21 15:50 +0200
        Re: [PATCH v3 3/7] kprobes: validate the symbol name length "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> - 2017-04-23 17:50 +0200
  Re: [PATCH v3 3/7] kprobes: validate the symbol name length Michael Ellerman <mpe@ellerman.id.au> - 2017-04-20 08:10 +0200
    Re: [PATCH v3 3/7] kprobes: validate the symbol name length "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> - 2017-04-20 09:30 +0200
  [PATCH v4 4/7] powerpc/kprobes: Use safer string functions in kprobe_lookup_name() "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> - 2017-04-21 14:40 +0200
    Re: [PATCH v4 4/7] powerpc/kprobes: Use safer string functions in  kprobe_lookup_name() Paul Clarke <pc@us.ibm.com> - 2017-04-21 15:40 +0200
      Re: [PATCH v4 4/7] powerpc/kprobes: Use safer string functions in  kprobe_lookup_name() Paul Clarke <pc@us.ibm.com> - 2017-04-21 15:40 +0200
      Re: [PATCH v4 4/7] powerpc/kprobes: Use safer string functions in  kprobe_lookup_name() Paul Clarke <pc@us.ibm.com> - 2017-04-21 16:00 +0200
        Re: [PATCH v4 4/7] powerpc/kprobes: Use safer string functions in  kprobe_lookup_name() "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> - 2017-04-23 19:20 +0200
  [PATCH v4 3/7] kprobes: validate the symbol name provided during probe registration "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> - 2017-04-21 14:40 +0200
    Re: [PATCH v4 3/7] kprobes: validate the symbol name provided during  probe registration Paul Clarke <pc@us.ibm.com> - 2017-04-21 15:20 +0200
      Re: [PATCH v4 3/7] kprobes: validate the symbol name provided during  probe registration "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> - 2017-04-21 15:30 +0200
    Re: [PATCH v4 3/7] kprobes: validate the symbol name provided  during probe registration Masami Hiramatsu <mhiramat@kernel.org> - 2017-04-21 16:00 +0200
    Re: [PATCH v4 3/7] kprobes: validate the symbol name provided during probe registration Michael Ellerman <mpe@ellerman.id.au> - 2017-04-22 08:00 +0200
      Re: [PATCH v4 3/7] kprobes: validate the symbol name provided during  probe registration "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> - 2017-04-23 19:50 +0200

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