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From: Bernd Edlinger <bernd.edlinger@hotmail.de>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Kirill Tkhai <ktkhai@virtuozzo.com>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	Christian Brauner <christian.brauner@ubuntu.com>,
	Kees Cook <keescook@chromium.org>, Jann Horn <jannh@google.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Andrew Morton <akpm@linux-foundation.org>,
	Alexey Dobriyan <adobriyan@gmail.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Oleg Nesterov <oleg@redhat.com>,
	Frederic Weisbecker <frederic@kernel.org>,
	Andrei Vagin <avagin@gmail.com>, Ingo Molnar <mingo@kernel.org>,
	"Peter Zijlstra (Intel)" <peterz@infradead.org>,
	Yuyang Du <duyuyang@gmail.com>,
	David Hildenbrand <david@redhat.com>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	Anshuman Khandual <anshuman.khandual@arm.com>,
	David Howells <dhowells@redhat.com>,
	James Morris <jamorris@linux.microsoft.com>,
	Shakeel Butt <shakeelb@google.com>,
	Jason Gunthorpe <jgg@ziepe.ca>,
	Christian Kellner <christian@kellner.me>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Aleksa Sarai <cyphar@cyphar.com>,
	"Dmitry V. Levin" <ldv@altlinux.org>,
	"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	"stable@vger.kernel.org" <stable@vger.kernel.org>,
	"linux-api@vger.kernel.org" <linux-api@vger.kernel.org>
Subject: [PATCH v6 13/16] perf: Use new infrastructure to fix deadlocks in execve
Date: Fri, 20 Mar 2020 21:27:55 +0100
Message-ID: <AM6PR03MB51704A188C3A1FA02B76B9EFE4F50@AM6PR03MB5170.eurprd03.prod.outlook.com> (raw)
In-Reply-To: <077b63b7-6f5e-aa8e-bf96-a586b481cc46@hotmail.de>

This changes perf_event_set_clock to use the new exec_update_mutex
instead of cred_guard_mutex.

This should be safe, as the credentials are only used for reading.

Signed-off-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
---
 kernel/events/core.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index e453589..71cba8c 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -1249,7 +1249,7 @@ static void put_ctx(struct perf_event_context *ctx)
  * function.
  *
  * Lock order:
- *    cred_guard_mutex
+ *    exec_update_mutex
  *	task_struct::perf_event_mutex
  *	  perf_event_context::mutex
  *	    perf_event::child_mutex;
@@ -11263,14 +11263,14 @@ static int perf_event_set_clock(struct perf_event *event, clockid_t clk_id)
 	}
 
 	if (task) {
-		err = mutex_lock_interruptible(&task->signal->cred_guard_mutex);
+		err = mutex_lock_interruptible(&task->signal->exec_update_mutex);
 		if (err)
 			goto err_task;
 
 		/*
 		 * Reuse ptrace permission checks for now.
 		 *
-		 * We must hold cred_guard_mutex across this and any potential
+		 * We must hold exec_update_mutex across this and any potential
 		 * perf_install_in_context() call for this new event to
 		 * serialize against exec() altering our credentials (and the
 		 * perf_event_exit_task() that could imply).
@@ -11559,7 +11559,7 @@ static int perf_event_set_clock(struct perf_event *event, clockid_t clk_id)
 	mutex_unlock(&ctx->mutex);
 
 	if (task) {
-		mutex_unlock(&task->signal->cred_guard_mutex);
+		mutex_unlock(&task->signal->exec_update_mutex);
 		put_task_struct(task);
 	}
 
@@ -11595,7 +11595,7 @@ static int perf_event_set_clock(struct perf_event *event, clockid_t clk_id)
 		free_event(event);
 err_cred:
 	if (task)
-		mutex_unlock(&task->signal->cred_guard_mutex);
+		mutex_unlock(&task->signal->exec_update_mutex);
 err_task:
 	if (task)
 		put_task_struct(task);
@@ -11900,7 +11900,7 @@ static void perf_event_exit_task_context(struct task_struct *child, int ctxn)
 /*
  * When a child task exits, feed back event values to parent events.
  *
- * Can be called with cred_guard_mutex held when called from
+ * Can be called with exec_update_mutex held when called from
  * install_exec_creds().
  */
 void perf_event_exit_task(struct task_struct *child)
-- 
1.9.1

  parent reply index

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <077b63b7-6f5e-aa8e-bf96-a586b481cc46@hotmail.de>
2020-03-20 20:24 ` [PATCH v6 01/16] exec: Only compute current once in flush_old_exec Bernd Edlinger
2020-03-20 20:24 ` [PATCH v6 02/16] exec: Factor unshare_sighand out of de_thread and call it separately Bernd Edlinger
2020-03-20 20:25 ` [PATCH v6 03/16] exec: Move cleanup of posix timers on exec out of de_thread Bernd Edlinger
2020-03-20 20:25 ` [PATCH v6 04/16] exec: Move exec_mmap right after de_thread in flush_old_exec Bernd Edlinger
2020-03-20 20:25 ` [PATCH v6 05/16] exec: Add exec_update_mutex to replace cred_guard_mutex Bernd Edlinger
2020-03-23 10:51   ` Kirill Tkhai
2020-03-20 20:26 ` [PATCH v6 06/16] exec: Fix a deadlock in strace Bernd Edlinger
2020-03-20 20:26 ` [PATCH v6 07/16] selftests/ptrace: add test cases for dead-locks Bernd Edlinger
2020-03-20 20:26 ` [PATCH v6 08/16] mm: docs: Fix a comment in process_vm_rw_core Bernd Edlinger
2020-03-20 20:26 ` [PATCH v6 09/16] kernel: doc: remove outdated comment cred.c Bernd Edlinger
2020-03-20 20:27 ` [PATCH v6 10/16] kernel/kcmp.c: Use new infrastructure to fix deadlocks in execve Bernd Edlinger
2020-03-25 15:41   ` Christian Brauner
2020-03-20 20:27 ` [PATCH v6 11/16] proc: " Bernd Edlinger
2020-03-20 20:27 ` [PATCH v6 12/16] proc: io_accounting: " Bernd Edlinger
2020-03-20 20:27 ` Bernd Edlinger [this message]
2020-03-21  2:46 ` [PATCH v6 14/16] pidfd: " Bernd Edlinger
2020-03-25 15:40   ` Christian Brauner
2020-03-21  2:46 ` [PATCH v6 15/16] exec: Fix dead-lock in de_thread with ptrace_attach Bernd Edlinger
2020-03-25 14:27   ` Eric W. Biederman
2020-03-29  4:31     ` Bernd Edlinger
2020-03-29  6:36       ` Bernd Edlinger
2020-03-30 18:26         ` [PATCH v7 " Bernd Edlinger
2020-03-21  2:47 ` [PATCH v6 16/16] doc: Update documentation of ->exec_*_mutex Bernd Edlinger

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