From: Ritesh Harjani <riteshh@linux.ibm.com>
To: linux-ext4@vger.kernel.org
Cc: tytso@mit.edu, jack@suse.cz, adilger.kernel@dilger.ca,
linux-fsdevel@vger.kernel.org,
Ritesh Harjani <riteshh@linux.ibm.com>
Subject: [PATCH] ext4: Unregister sysfs path before destroying jbd2 journal
Date: Wed, 18 Mar 2020 11:43:01 +0530 [thread overview]
Message-ID: <20200318061301.4320-1-riteshh@linux.ibm.com> (raw)
Call ext4_unregister_sysfs(), before destroying jbd2 journal,
since below might cause, NULL pointer dereference issue.
This got reported with LTP tests.
ext4_put_super() cat /sys/fs/ext4/loop2/journal_task
| ext4_attr_show();
ext4_jbd2_journal_destroy(); |
| journal_task_show()
| |
| task_pid_vnr(NULL);
sbi->s_journal = NULL;
Signed-off-by: Ritesh Harjani <riteshh@linux.ibm.com>
---
fs/ext4/super.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 5dc65b7583cb..27ab130a40d1 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1024,6 +1024,13 @@ static void ext4_put_super(struct super_block *sb)
destroy_workqueue(sbi->rsv_conversion_wq);
+ /*
+ * Unregister sysfs before destroying jbd2 journal.
+ * Since we could still access attr_journal_task attribute via sysfs
+ * path which could have sbi->s_journal->j_task as NULL
+ */
+ ext4_unregister_sysfs(sb);
+
if (sbi->s_journal) {
aborted = is_journal_aborted(sbi->s_journal);
err = jbd2_journal_destroy(sbi->s_journal);
@@ -1034,7 +1041,6 @@ static void ext4_put_super(struct super_block *sb)
}
}
- ext4_unregister_sysfs(sb);
ext4_es_unregister_shrinker(sbi);
del_timer_sync(&sbi->s_err_report);
ext4_release_system_zone(sb);
--
2.21.0
next reply other threads:[~2020-03-18 6:13 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-18 6:13 Ritesh Harjani [this message]
2020-03-18 9:13 ` [PATCH] ext4: Unregister sysfs path before destroying jbd2 journal Jan Kara
2020-03-26 14:53 ` Theodore Y. Ts'o
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