Messages in this thread | | | Date | Mon, 08 Apr 2013 12:03:55 +0800 | From | Chen Gang <> | Subject | Re: [PATCH] kernel: tsacct: strncpy, always be sure of NUL terminated. |
| |
On 2013年04月08日 11:52, KOSAKI Motohiro wrote: > On Sun, Apr 7, 2013 at 11:27 PM, Chen Gang <gang.chen@asianux.com> wrote: >> > >> > for NUL terminated string, always set '\0' at the end. >> > >> > Signed-off-by: Chen Gang <gang.chen@asianux.com> >> > --- >> > kernel/tsacct.c | 3 ++- >> > 1 files changed, 2 insertions(+), 1 deletions(-) >> > >> > diff --git a/kernel/tsacct.c b/kernel/tsacct.c >> > index a1dd9a1..01bcc4e 100644 >> > --- a/kernel/tsacct.c >> > +++ b/kernel/tsacct.c >> > @@ -78,7 +78,8 @@ void bacct_add_tsk(struct user_namespace *user_ns, >> > stats->ac_minflt = tsk->min_flt; >> > stats->ac_majflt = tsk->maj_flt; >> > >> > - strncpy(stats->ac_comm, tsk->comm, sizeof(stats->ac_comm)); >> > + strncpy(stats->ac_comm, tsk->comm, sizeof(stats->ac_comm) - 1); >> > + stats->ac_comm[sizeof(stats->ac_comm) - 1] = '\0'; > sizeof(tsk->comm) is 16 and sizeof(stats->ac_comm) is 32. then this statement > is strange. and set_task_comm ensure tsk->comm is nul-terminated. > > so your code never change the behavior, right? >
right.
thank you for your information: originally, I really did not check the sizeof details.
> And, If buggy driver change tsk->comm not to use set_task_comm and tsk->comm > is not nul-terminated, strncpy() still touch unrelated memory and ac_comm may > expose kernel internal info. that's bad. > >
really, that's bad !
thank you for your information: originally, I did not think of a buggy driver can change tsk->comm.
:-)
-- Chen Gang
Asianux Corporation -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |