linux-kernel - Re: [PATCH bpf-next 1/2] bpf: Add bpf_task_cwd_from

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <202505300432.nZC50gOu-lkp@intel.com>
Date: Mon, 2 Jun 2025 09:20:10 +0300
From: Dan Carpenter <dan.carpenter@...aro.org>
To: oe-kbuild@...ts.linux.dev, Rong Tao <rtoax@...mail.com>, ast@...nel.org,
	daniel@...earbox.net
Cc: lkp@...el.com, oe-kbuild-all@...ts.linux.dev, rtoax@...mail.com,
	rongtao@...tc.cn, Andrii Nakryiko <andrii@...nel.org>,
	Martin KaFai Lau <martin.lau@...ux.dev>,
	Eduard Zingerman <eddyz87@...il.com>, Song Liu <song@...nel.org>,
	Yonghong Song <yonghong.song@...ux.dev>,
	John Fastabend <john.fastabend@...il.com>,
	KP Singh <kpsingh@...nel.org>, Stanislav Fomichev <sdf@...ichev.me>,
	Hao Luo <haoluo@...gle.com>, Jiri Olsa <jolsa@...nel.org>,
	Mykola Lysenko <mykolal@...com>,
	Shuah Khan <skhan@...uxfoundation.org>,
	Juntong Deng <juntong.deng@...look.com>,
	Amery Hung <amery.hung@...edance.com>,
	Dave Marchevsky <davemarchevsky@...com>,
	Hou Tao <houtao1@...wei.com>,
	"(open list:BPF (Safe Dynamic Programs and Tools))" <bpf@...r.kernel.org>,
	linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH bpf-next 1/2] bpf: Add bpf_task_cwd_from_pid() kfunc

Hi Rong,

kernel test robot noticed the following build warnings:

url:    https://github.com/intel-lab-lkp/linux/commits/Rong-Tao/selftests-bpf-Add-selftests-for-bpf_task_cwd_from_pid/20250529-113933
base:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
patch link:    https://lore.kernel.org/r/tencent_97F8B56B340F51DB604B482FEBF012460505%40qq.com
patch subject: [PATCH bpf-next 1/2] bpf: Add bpf_task_cwd_from_pid() kfunc
config: x86_64-randconfig-161-20250529 (https://download.01.org/0day-ci/archive/20250530/202505300432.nZC50gOu-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@...el.com>
| Reported-by: Dan Carpenter <dan.carpenter@...aro.org>
| Closes: https://lore.kernel.org/r/202505300432.nZC50gOu-lkp@intel.com/

smatch warnings:
kernel/bpf/helpers.c:2687 bpf_task_cwd_from_pid() warn: inconsistent returns 'rcu_read'.

vim +/rcu_read +2687 kernel/bpf/helpers.c

b24383bde5a454 Rong Tao     2025-05-29  2657  __bpf_kfunc int bpf_task_cwd_from_pid(s32 pid, char *buf, u32 buf_len)
b24383bde5a454 Rong Tao     2025-05-29  2658  {
b24383bde5a454 Rong Tao     2025-05-29  2659  	struct path pwd;
b24383bde5a454 Rong Tao     2025-05-29  2660  	char kpath[256], *path;
b24383bde5a454 Rong Tao     2025-05-29  2661  	struct task_struct *task;
b24383bde5a454 Rong Tao     2025-05-29  2662  
b24383bde5a454 Rong Tao     2025-05-29  2663  	if (!buf || buf_len == 0)
b24383bde5a454 Rong Tao     2025-05-29  2664  		return -EINVAL;
b24383bde5a454 Rong Tao     2025-05-29  2665  
b24383bde5a454 Rong Tao     2025-05-29  2666  	rcu_read_lock();
b24383bde5a454 Rong Tao     2025-05-29  2667  	task = pid_task(find_vpid(pid), PIDTYPE_PID);
b24383bde5a454 Rong Tao     2025-05-29  2668  	if (!task) {
b24383bde5a454 Rong Tao     2025-05-29  2669  		rcu_read_unlock();
b24383bde5a454 Rong Tao     2025-05-29  2670  		return -ESRCH;
b24383bde5a454 Rong Tao     2025-05-29  2671  	}
b24383bde5a454 Rong Tao     2025-05-29  2672  	task_lock(task);
b24383bde5a454 Rong Tao     2025-05-29  2673  	if (!task->fs) {
b24383bde5a454 Rong Tao     2025-05-29  2674  		task_unlock(task);
b24383bde5a454 Rong Tao     2025-05-29  2675  		return -ENOENT;

rcu_read_unlock();

b24383bde5a454 Rong Tao     2025-05-29  2676  	}
b24383bde5a454 Rong Tao     2025-05-29  2677  	get_fs_pwd(task->fs, &pwd);
b24383bde5a454 Rong Tao     2025-05-29  2678  	task_unlock(task);
b24383bde5a454 Rong Tao     2025-05-29  2679  	rcu_read_unlock();
b24383bde5a454 Rong Tao     2025-05-29  2680  
b24383bde5a454 Rong Tao     2025-05-29  2681  	path = d_path(&pwd, kpath, sizeof(kpath));
b24383bde5a454 Rong Tao     2025-05-29  2682  	path_put(&pwd);
b24383bde5a454 Rong Tao     2025-05-29  2683  	if (IS_ERR(path))
b24383bde5a454 Rong Tao     2025-05-29  2684  		return PTR_ERR(path);
b24383bde5a454 Rong Tao     2025-05-29  2685  
b24383bde5a454 Rong Tao     2025-05-29  2686  	strncpy(buf, path, buf_len);
b24383bde5a454 Rong Tao     2025-05-29 @2687  	return 0;
b24383bde5a454 Rong Tao     2025-05-29  2688  }

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki