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

[Naveen N. Rao]

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