Messages in this thread | | | Subject | Re: [PATCH v4 4/7] powerpc/kprobes: Use safer string functions in kprobe_lookup_name() | From | Paul Clarke <> | Date | Fri, 21 Apr 2017 08:33:22 -0500 |
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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. > > Reported-by: David Laight <David.Laight@ACULAB.COM> > Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> > --- > Changes: Additionally convert the strchr(). > > > arch/powerpc/kernel/kprobes.c | 13 ++++++------- > 1 file changed, 6 insertions(+), 7 deletions(-) > > 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) { > modsym++; > if (*modsym != '\0' && *modsym != '.') { > /* Convert to <module:.symbol> */ > - strncpy(dot_name, name, modsym - name); > + memcpy(dot_name, name, modsym - name); > dot_name[modsym - name] = '.'; > dot_name[modsym - name + 1] = '\0'; > - strncat(dot_name, modsym, > - sizeof(dot_name) - (modsym - name) - 2); > + strlcat(dot_name, modsym, sizeof(dot_name));
Would it be more efficient here to replace this: -- dot_name[modsym - name + 1] = '\0'; strlcat(dot_name, modsym, sizeof(dot_name)); --
with this: strncpy(&dot_name[modsym - name + 1], modsym, KSYM_NAME_LEN);
(So you aren't rescanning dot_name to find the end, when you already know the end position?)
> dot_appended = true; > } else { > dot_name[0] = '\0'; > - strncat(dot_name, name, sizeof(dot_name) - 1); > + strlcat(dot_name, name, sizeof(dot_name));
and here do: strncpy(dot_name, name, sizeof(dot_name));
(and remove the null termination immediately above)
> } > } else if (name[0] != '.') { > dot_name[0] = '.'; > dot_name[1] = '\0'; > - strncat(dot_name, name, KSYM_NAME_LEN - 2); > + strlcat(dot_name, name, sizeof(dot_name));
and here do: strncpy(&dot_name[1], name, sizeof(dot_name));
(and remove the null termination immediately above)
> dot_appended = true; > } else { > dot_name[0] = '\0'; > - strncat(dot_name, name, KSYM_NAME_LEN - 1); > + strlcat(dot_name, name, sizeof(dot_name));
and here do: strncpy(dot_name, name, sizeof(dot_name));
(and remove the null termination immediately above)
> }
PC
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