On Thu, Nov 11, 2021 at 7:47 PM David Hildenbrand <david@xxxxxxxxxx> wrote: > > On 11.11.21 12:34, Petr Mladek wrote: > > On Thu 2021-11-11 11:06:04, David Hildenbrand wrote: > >> On 11.11.21 11:03, David Hildenbrand wrote: > >>> On 08.11.21 09:38, Yafang Shao wrote: > >>>> It is better to use get_task_comm() instead of the open coded string > >>>> copy as we do in other places. > >>>> > >>>> struct elf_prpsinfo is used to dump the task information in userspace > >>>> coredump or kernel vmcore. Below is the verfication of vmcore, > >>>> > >>>> crash> ps > >>>> PID PPID CPU TASK ST %MEM VSZ RSS COMM > >>>> 0 0 0 ffffffff9d21a940 RU 0.0 0 0 [swapper/0] > >>>>> 0 0 1 ffffa09e40f85e80 RU 0.0 0 0 [swapper/1] > >>>>> 0 0 2 ffffa09e40f81f80 RU 0.0 0 0 [swapper/2] > >>>>> 0 0 3 ffffa09e40f83f00 RU 0.0 0 0 [swapper/3] > >>>>> 0 0 4 ffffa09e40f80000 RU 0.0 0 0 [swapper/4] > >>>>> 0 0 5 ffffa09e40f89f80 RU 0.0 0 0 [swapper/5] > >>>> 0 0 6 ffffa09e40f8bf00 RU 0.0 0 0 [swapper/6] > >>>>> 0 0 7 ffffa09e40f88000 RU 0.0 0 0 [swapper/7] > >>>>> 0 0 8 ffffa09e40f8de80 RU 0.0 0 0 [swapper/8] > >>>>> 0 0 9 ffffa09e40f95e80 RU 0.0 0 0 [swapper/9] > >>>>> 0 0 10 ffffa09e40f91f80 RU 0.0 0 0 [swapper/10] > >>>>> 0 0 11 ffffa09e40f93f00 RU 0.0 0 0 [swapper/11] > >>>>> 0 0 12 ffffa09e40f90000 RU 0.0 0 0 [swapper/12] > >>>>> 0 0 13 ffffa09e40f9bf00 RU 0.0 0 0 [swapper/13] > >>>>> 0 0 14 ffffa09e40f98000 RU 0.0 0 0 [swapper/14] > >>>>> 0 0 15 ffffa09e40f9de80 RU 0.0 0 0 [swapper/15] > >>>> > >>>> It works well as expected. > >>>> > >>>> Suggested-by: Kees Cook <keescook@xxxxxxxxxxxx> > >>>> Signed-off-by: Yafang Shao <laoar.shao@xxxxxxxxx> > >>>> Cc: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx> > >>>> Cc: Arnaldo Carvalho de Melo <arnaldo.melo@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/binfmt_elf.c | 2 +- > >>>> 1 file changed, 1 insertion(+), 1 deletion(-) > >>>> > >>>> diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c > >>>> index a813b70f594e..138956fd4a88 100644 > >>>> --- a/fs/binfmt_elf.c > >>>> +++ b/fs/binfmt_elf.c > >>>> @@ -1572,7 +1572,7 @@ static int fill_psinfo(struct elf_prpsinfo *psinfo, struct task_struct *p, > >>>> SET_UID(psinfo->pr_uid, from_kuid_munged(cred->user_ns, cred->uid)); > >>>> SET_GID(psinfo->pr_gid, from_kgid_munged(cred->user_ns, cred->gid)); > >>>> rcu_read_unlock(); > >>>> - strncpy(psinfo->pr_fname, p->comm, sizeof(psinfo->pr_fname)); > >>>> + get_task_comm(psinfo->pr_fname, p); > >>>> > >>>> return 0; > >>>> } > >>>> > >>> > >>> We have a hard-coded "pr_fname[16]" as well, not sure if we want to > >>> adjust that to use TASK_COMM_LEN? > >> > >> But if the intention is to chance TASK_COMM_LEN later, we might want to > >> keep that unchanged. > > > > It seems that len will not change in the end. Another solution is > > going to be used for the long names, see > > https://lore.kernel.org/r/20211108084142.4692-1-laoar.shao@xxxxxxxxx. > > Yes, that's what I recall as well. The I read the patch > subjects+descriptions in this series "make it adopt to task comm size > change" and was slightly confused. > > Maybe we should just remove any notion of "task comm size change" from > this series and instead just call it a cleanup. > > Agreed that it may make a little confused for the one who didn't engage in this series at the first place. I will improve the subjection+description. -- Thanks Yafang
