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. -- Thanks, David / dhildenb
