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From:   Dietmar Eggemann <dietmar.eggemann@arm.com>
To:     Ingo Molnar <mingo@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>
Cc:     Juri Lelli <juri.lelli@redhat.com>,
        Vincent Guittot <vincent.guittot@linaro.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Valentin Schneider <valentin.schneider@arm.com>,
        linux-kernel@vger.kernel.org
Subject: [PATCH] debugfs: Fix debugfs_read_file_str()
Date:   Thu, 27 May 2021 11:11:05 +0200
Message-Id: <20210527091105.258457-1-dietmar.eggemann@arm.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

Read the entire size of the buffer, including the trailing new line
character.
Discovered while reading the sched domain names of CPU0:

before:

cat /sys/kernel/debug/sched/domains/cpu0/domain*/name
SMTMCDIE

after:

cat /sys/kernel/debug/sched/domains/cpu0/domain*/name
SMT
MC
DIE

Fixes: 9af0440ec86eb ("debugfs: Implement debugfs_create_str()")
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
---
 fs/debugfs/file.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c
index e813acfaa6e8..ba7c01cd9a5d 100644
--- a/fs/debugfs/file.c
+++ b/fs/debugfs/file.c
@@ -893,7 +893,7 @@ ssize_t debugfs_read_file_str(struct file *file, char __user *user_buf,
 
 	copy[copy_len] = '\n';
 
-	ret = simple_read_from_buffer(user_buf, count, ppos, copy, copy_len);
+	ret = simple_read_from_buffer(user_buf, count, ppos, copy, len);
 	kfree(copy);
 
 	return ret;
-- 
2.25.1