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Message-Id: <20211101060419.4682-6-laoar.shao@gmail.com>
Date: Mon, 1 Nov 2021 06:04:13 +0000
From: Yafang Shao <laoar.shao@...il.com>
To: akpm@...ux-foundation.org, keescook@...omium.org,
rostedt@...dmis.org, mathieu.desnoyers@...icios.com,
arnaldo.melo@...il.com, pmladek@...e.com, peterz@...radead.org,
viro@...iv.linux.org.uk, valentin.schneider@....com,
qiang.zhang@...driver.com, robdclark@...omium.org,
christian@...uner.io, dietmar.eggemann@....com, mingo@...hat.com,
juri.lelli@...hat.com, vincent.guittot@...aro.org,
davem@...emloft.net, kuba@...nel.org, ast@...nel.org,
daniel@...earbox.net, andrii@...nel.org, kafai@...com,
songliubraving@...com, yhs@...com, john.fastabend@...il.com,
kpsingh@...nel.org, dennis.dalessandro@...nelisnetworks.com,
mike.marciniszyn@...nelisnetworks.com, dledford@...hat.com,
jgg@...pe.ca
Cc: linux-rdma@...r.kernel.org, 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,
Yafang Shao <laoar.shao@...il.com>,
Andrii Nakryiko <andrii.nakryiko@...il.com>
Subject: [PATCH v7 05/11] fs/binfmt_elf: make prpsinfo always get a nul terminated task comm
kernel test robot reported a -Wstringop-truncation warning after I
extend task comm from 16 to 24. Below is the detailed warning:
fs/binfmt_elf.c: In function 'fill_psinfo.isra':
>> fs/binfmt_elf.c:1575:9: warning: 'strncpy' output may be truncated copying 16 bytes from a string of length 23 [-Wstringop-truncation]
1575 | strncpy(psinfo->pr_fname, p->comm, sizeof(psinfo->pr_fname));
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Replacing the open-coded strncpy() with the helper get_task_comm() can
avoid this warning.
As the struct prpsinfo is externally parsed, for example by the crash
utility, we can't change the size of pr_fname. So I just leave it as-is.
I also verfied if it still work well when I extend the comm size to 24.
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.
Reported-by: kernel test robot <lkp@...el.com>
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: Peter Zijlstra <peterz@...radead.org>
Cc: Steven Rostedt <rostedt@...dmis.org>
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;
}
--
2.17.1
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