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[79.242.62.232]) by smtp.gmail.com with ESMTPSA id l15sm2324926wme.47.2021.11.11.02.06.05 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 11 Nov 2021 02:06:05 -0800 (PST) Message-ID: Date: Thu, 11 Nov 2021 11:06:04 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.2.0 Subject: Re: [PATCH 4/7] fs/binfmt_elf: use get_task_comm instead of open-coded string copy From: David Hildenbrand To: Yafang Shao , akpm@linux-foundation.org Cc: netdev@vger.kernel.org, bpf@vger.kernel.org, linux-perf-users@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, oliver.sang@intel.com, lkp@intel.com, Kees Cook , Mathieu Desnoyers , Arnaldo Carvalho de Melo , Andrii Nakryiko , Michal Miroslaw , Peter Zijlstra , Steven Rostedt , Matthew Wilcox , Al Viro , Petr Mladek References: <20211108083840.4627-1-laoar.shao@gmail.com> <20211108083840.4627-5-laoar.shao@gmail.com> Organization: Red Hat In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 6BEF1F000090 X-Stat-Signature: 9rmr67sqr4y4sq8tbobnr36wdk5uqccc Authentication-Results: imf16.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=g7TJ4wFi; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=D+cB4Yko; spf=none (imf16.hostedemail.com: domain of david@redhat.com has no SPF policy when checking 170.10.133.124) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=none) header.from=redhat.com X-HE-Tag: 1636625166-821560 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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 >> Signed-off-by: Yafang Shao >> Cc: Mathieu Desnoyers >> Cc: Arnaldo Carvalho de Melo >> Cc: Andrii Nakryiko >> Cc: Michal Miroslaw >> Cc: Peter Zijlstra >> Cc: Steven Rostedt >> Cc: Matthew Wilcox >> Cc: David Hildenbrand >> Cc: Al Viro >> Cc: Kees Cook >> Cc: Petr Mladek >> --- >> 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. (replacing the 16 by a define might still be a good idea, similar to how it's done for ELF_PRARGSZ, but just a thought) -- Thanks, David / dhildenb