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From: Yafang Shao <laoar.shao@gmail.com>
To: akpm@linux-foundation.org, pmladek@suse.com,
	peterz@infradead.org, valentin.schneider@arm.com,
	keescook@chromium.org, mathieu.desnoyers@efficios.com,
	qiang.zhang@windriver.com, robdclark@chromium.org,
	viro@zeniv.linux.org.uk, christian@brauner.io,
	dietmar.eggemann@arm.com
Cc: linux-kernel@vger.kernel.org, Yafang Shao <laoar.shao@gmail.com>
Subject: [PATCH 2/5] kernel/fork: allocate task->comm dynamicly
Date: Wed, 29 Sep 2021 11:50:33 +0000	[thread overview]
Message-ID: <20210929115036.4851-3-laoar.shao@gmail.com> (raw)
In-Reply-To: <20210929115036.4851-1-laoar.shao@gmail.com>

task->comm is defined as an array embedded in struct task_struct before.
This patch changes it to a char pointer. It will be allocated in the fork
and freed when the task is freed.

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
---
 include/linux/sched.h |  2 +-
 kernel/fork.c         | 19 +++++++++++++++++++
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index e12b524426b0..b387b5943db4 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1051,7 +1051,7 @@ struct task_struct {
 	 * - access it with [gs]et_task_comm()
 	 * - lock it with task_lock()
 	 */
-	char				comm[TASK_COMM_LEN];
+	char				*comm;
 
 	struct nameidata		*nameidata;
 
diff --git a/kernel/fork.c b/kernel/fork.c
index 38681ad44c76..227aec240501 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -721,6 +721,20 @@ static void mmdrop_async(struct mm_struct *mm)
 	}
 }
 
+static int task_comm_alloc(struct task_struct *p)
+{
+	p->comm = kzalloc(TASK_COMM_LEN, GFP_KERNEL);
+	if (!p->comm)
+		return -ENOMEM;
+
+	return 0;
+}
+
+static void task_comm_free(struct task_struct *p)
+{
+	kfree(p->comm);
+}
+
 static inline void free_signal_struct(struct signal_struct *sig)
 {
 	taskstats_tgid_free(sig);
@@ -753,6 +767,7 @@ void __put_task_struct(struct task_struct *tsk)
 	bpf_task_storage_free(tsk);
 	exit_creds(tsk);
 	delayacct_tsk_free(tsk);
+	task_comm_free(tsk);
 	put_signal_struct(tsk->signal);
 	sched_core_free(tsk);
 
@@ -2076,6 +2091,10 @@ static __latent_entropy struct task_struct *copy_process(
 	if (data_race(nr_threads >= max_threads))
 		goto bad_fork_cleanup_count;
 
+	retval = task_comm_alloc(p);
+	if (retval)
+		goto bad_fork_cleanup_count;
+
 	delayacct_tsk_init(p);	/* Must remain after dup_task_struct() */
 	p->flags &= ~(PF_SUPERPRIV | PF_WQ_WORKER | PF_IDLE | PF_NO_SETAFFINITY);
 	p->flags |= PF_FORKNOEXEC;
-- 
2.17.1


  parent reply	other threads:[~2021-09-29 11:51 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-29 11:50 [PATCH 0/5] kthread: increase the size of kthread's comm Yafang Shao
2021-09-29 11:50 ` [PATCH 1/5] kernel: replace sizeof(task->comm) with TASK_COMM_LEN Yafang Shao
2021-09-29 18:09   ` Kees Cook
2021-09-30 12:27     ` Yafang Shao
2021-10-03  3:31   ` Al Viro
2021-10-03 14:14     ` Yafang Shao
2021-09-29 11:50 ` Yafang Shao [this message]
2021-09-29 13:08   ` [PATCH 2/5] kernel/fork: allocate task->comm dynamicly Yafang Shao
2021-09-29 18:11   ` Kees Cook
2021-09-30 12:41     ` Yafang Shao
2021-09-30 14:51       ` Petr Mladek
2021-10-01 11:58         ` Yafang Shao
2021-09-29 11:50 ` [PATCH 3/5] kernel/sched: improve the BUILD_BUG_ON() in get_task_comm() Yafang Shao
2021-09-29 18:12   ` Kees Cook
2021-09-30 12:43     ` Yafang Shao
2021-09-29 11:50 ` [PATCH 4/5] kernel: increase the size of kthread's comm Yafang Shao
2021-09-29 18:19   ` Kees Cook
2021-09-30 12:53     ` Yafang Shao
2021-09-29 11:50 ` [PATCH 5/5] kernel/kthread: show a warning if kthread's comm is still trucated Yafang Shao
2021-09-29 18:20   ` Kees Cook
2021-09-30 12:54     ` Yafang Shao
2021-09-30 15:17   ` Petr Mladek
2021-10-01 11:59     ` Yafang Shao
2021-10-03  3:41 ` [PATCH 0/5] kthread: increase the size of kthread's comm Al Viro
2021-10-03 14:20   ` Yafang Shao

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