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Date: Thu, 11 Nov 2021 11:03:53 +0100
From: David Hildenbrand <david@...hat.com>
To: Yafang Shao <laoar.shao@...il.com>, akpm@...ux-foundation.org
Cc: netdev@...r.kernel.org, bpf@...r.kernel.org,
linux-perf-users@...r.kernel.org, linux-fsdevel@...r.kernel.org,
linux-mm@...ck.org, linux-kernel@...r.kernel.org,
oliver.sang@...el.com, lkp@...el.com,
Kees Cook <keescook@...omium.org>,
Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>,
Andrii Nakryiko <andrii.nakryiko@...il.com>,
Michal Miroslaw <mirq-linux@...e.qmqm.pl>,
Peter Zijlstra <peterz@...radead.org>,
Steven Rostedt <rostedt@...dmis.org>,
Matthew Wilcox <willy@...radead.org>,
Al Viro <viro@...iv.linux.org.uk>,
Petr Mladek <pmladek@...e.com>
Subject: Re: [PATCH 4/7] fs/binfmt_elf: use get_task_comm instead of
open-coded string copy
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@...omium.org>
> Signed-off-by: Yafang Shao <laoar.shao@...il.com>
> Cc: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
> Cc: Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>
> Cc: Andrii Nakryiko <andrii.nakryiko@...il.com>
> Cc: Michal Miroslaw <mirq-linux@...e.qmqm.pl>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Cc: Steven Rostedt <rostedt@...dmis.org>
> Cc: Matthew Wilcox <willy@...radead.org>
> Cc: David Hildenbrand <david@...hat.com>
> Cc: Al Viro <viro@...iv.linux.org.uk>
> Cc: Kees Cook <keescook@...omium.org>
> Cc: Petr Mladek <pmladek@...e.com>
> ---
> 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?
Anyhow
Reviewed-by: David Hildenbrand <david@...hat.com>
--
Thanks,
David / dhildenb
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