On Wed, Nov 10, 2021 at 4:28 PM David Hildenbrand <david@xxxxxxxxxx> wrote: > > On 08.11.21 09:38, Yafang Shao wrote: > > Make sure the string set to task comm is always nul terminated. > > > > strlcpy: "the result is always a valid NUL-terminated string that fits > in the buffer" > > The only difference seems to be that strscpy_pad() pads the remainder > with zeroes. > > Is this description correct and I am missing something important? > In a earlier version [1], the checkpatch.py found a warning: WARNING: Prefer strscpy over strlcpy - see: https://lore.kernel.org/r/CAHk-=wgfRnXz0W3D37d01q3JFkr_i_uTL=V6A6G1oUZcprmknw@xxxxxxxxxxxxxx/ So I replaced strlcpy() with strscpy() to fix this warning. And then in v5[2], the strscpy() was replaced with strscpy_pad() to make sure there's no garbade data and also make get_task_comm() be consistent with get_task_comm(). This commit log didn't clearly describe the historical changes. So I think we can update the commit log and subject with: Subject: use strscpy_pad with strlcpy in __set_task_comm Commit log: strlcpy is not suggested to use by the checkpatch.pl, so we'd better recplace it with strscpy. To avoid leaving garbage data and be consistent with the usage in __get_task_comm(), the strscpy_pad is used here. WDYT? [1]. https://lore.kernel.org/lkml/20211007120752.5195-3-laoar.shao@xxxxxxxxx/ [2]. https://lore.kernel.org/lkml/20211021034516.4400-2-laoar.shao@xxxxxxxxx/ > > Signed-off-by: Yafang Shao <laoar.shao@xxxxxxxxx> > > Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx> > > Cc: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx> > > Cc: Arnaldo Carvalho de Melo <arnaldo.melo@xxxxxxxxx> > > Cc: Alexei Starovoitov <alexei.starovoitov@xxxxxxxxx> > > Cc: Andrii Nakryiko <andrii.nakryiko@xxxxxxxxx> > > Cc: Michal Miroslaw <mirq-linux@xxxxxxxxxxxx> > > Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> > > Cc: Steven Rostedt <rostedt@xxxxxxxxxxx> > > Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx> > > Cc: David Hildenbrand <david@xxxxxxxxxx> > > Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx> > > Cc: Kees Cook <keescook@xxxxxxxxxxxx> > > Cc: Petr Mladek <pmladek@xxxxxxxx> > > --- > > fs/exec.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/fs/exec.c b/fs/exec.c > > index a098c133d8d7..404156b5b314 100644 > > --- a/fs/exec.c > > +++ b/fs/exec.c > > @@ -1224,7 +1224,7 @@ void __set_task_comm(struct task_struct *tsk, const char *buf, bool exec) > > { > > task_lock(tsk); > > trace_task_rename(tsk, buf); > > - strlcpy(tsk->comm, buf, sizeof(tsk->comm)); > > + strscpy_pad(tsk->comm, buf, sizeof(tsk->comm)); > > task_unlock(tsk); > > perf_event_comm(tsk, exec); > > } > > > > > -- > Thanks, > > David / dhildenb > -- Thanks Yafang
