From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Alexey Dobriyan , "Eric W. Biederman" , Andrew Morton , Linus Torvalds , Sasha Levin Subject: [PATCH 4.14 046/189] proc: revalidate kernel thread inodes to root:root Date: Mon, 18 Jun 2018 10:12:22 +0200 Message-Id: <20180618081211.193806618@linuxfoundation.org> In-Reply-To: <20180618081209.254234434@linuxfoundation.org> References: <20180618081209.254234434@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Alexey Dobriyan [ Upstream commit 2e0ad552f5f8cd0fda02bc45fcd2b89821c62fd1 ] task_dump_owner() has the following code: mm = task->mm; if (mm) { if (get_dumpable(mm) != SUID_DUMP_USER) { uid = ... } } Check for ->mm is buggy -- kernel thread might be borrowing mm and inode will go to some random uid:gid pair. Link: http://lkml.kernel.org/r/20180412220109.GA20978@avx2 Signed-off-by: Alexey Dobriyan Cc: "Eric W. Biederman" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- fs/proc/base.c | 6 ++++++ 1 file changed, 6 insertions(+) --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -1694,6 +1694,12 @@ void task_dump_owner(struct task_struct kuid_t uid; kgid_t gid; + if (unlikely(task->flags & PF_KTHREAD)) { + *ruid = GLOBAL_ROOT_UID; + *rgid = GLOBAL_ROOT_GID; + return; + } + /* Default to the tasks effective ownership */ rcu_read_lock(); cred = __task_cred(task);