[PATCH AUTOSEL 5.13 119/189] ext4: fix memory leak in ext4_fill_super

Sasha Levin
2021-07-06T11:22:47Z

From: Pavel Skripkin <paskripkin@gmail.com>

[ Upstream commit 618f003199c6188e01472b03cdbba227f1dc5f24 ]

static int kthread(void *_create) will return -ENOMEM
or -EINTR in case of internal failure or
kthread_stop() call happens before threadfn call.

To prevent fancy error checking and make code
more straightforward we moved all cleanup code out
of kmmpd threadfn.

Also, dropped struct mmpd_data at all. Now struct super_block
is a threadfn data and struct buffer_head embedded into
struct ext4_sb_info.

Reported-by: syzbot+d9e482e303930fa4f6ff@syzkaller.appspotmail.com
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
Link: https://lore.kernel.org/r/20210430185046.15742-1-paskripkin@gmail.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/ext4/ext4.h | 4 ++++
fs/ext4/mmp.c | 28 +++++++++++++---------------
fs/ext4/super.c | 10 ++++------
3 files changed, 21 insertions(+), 21 deletions(-)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 37002663d521..a179c0bbc12e 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1488,6 +1488,7 @@ struct ext4_sb_info {
struct kobject s_kobj;
struct completion s_kobj_unregister;
struct super_block *s_sb;
+ struct buffer_head *s_mmp_bh;

/* Journaling */
struct journal_s *s_journal;
@@ -3720,6 +3721,9 @@ extern struct ext4_io_end_vec *ext4_last_io_end_vec(ext4_io_end_t *io_end);
/* mmp.c */
extern int ext4_multi_mount_protect(struct super_block *, ext4_fsblk_t);

+/* mmp.c */
+extern void ext4_stop_mmpd(struct ext4_sb_info *sbi);
+
/* verity.c */
extern const struct fsverity_operations ext4_verityops;

diff --git a/fs/ext4/mmp.c b/fs/ext4/mmp.c
index 68fbeedd627b..6cb598b549ca 100644
--- a/fs/ext4/mmp.c
+++ b/fs/ext4/mmp.c
@@ -127,9 +127,9 @@ void __dump_mmp_msg(struct super_block *sb, struct mmp_struct *mmp,
*/
static int kmmpd(void *data)
{
- struct super_block *sb = ((struct mmpd_data *) data)->sb;
- struct buffer_head *bh = ((struct mmpd_data *) data)->bh;
+ struct super_block *sb = (struct super_block *) data;
struct ext4_super_block *es = EXT4_SB(sb)->s_es;
+ struct buffer_head *bh = EXT4_SB(sb)->s_mmp_bh;
struct mmp_struct *mmp;
ext4_fsblk_t mmp_block;
u32 seq = 0;
@@ -245,12 +245,18 @@ static int kmmpd(void *data)
retval = write_mmp_block(sb, bh);

exit_thread:
- EXT4_SB(sb)->s_mmp_tsk = NULL;
- kfree(data);
- brelse(bh);
return retval;
}

+void ext4_stop_mmpd(struct ext4_sb_info *sbi)
+{
+ if (sbi->s_mmp_tsk) {
+ kthread_stop(sbi->s_mmp_tsk);
+ brelse(sbi->s_mmp_bh);
+ sbi->s_mmp_tsk = NULL;
+ }
+}
+
/*
* Get a random new sequence number but make sure it is not greater than
* EXT4_MMP_SEQ_MAX.
@@ -275,7 +281,6 @@ int ext4_multi_mount_protect(struct super_block *sb,
struct ext4_super_block *es = EXT4_SB(sb)->s_es;
struct buffer_head *bh = NULL;
struct mmp_struct *mmp = NULL;
- struct mmpd_data *mmpd_data;
u32 seq;
unsigned int mmp_check_interval = le16_to_cpu(es->s_mmp_update_interval);
unsigned int wait_time = 0;
@@ -364,24 +369,17 @@ int ext4_multi_mount_protect(struct super_block *sb,
goto failed;
}

- mmpd_data = kmalloc(sizeof(*mmpd_data), GFP_KERNEL);
- if (!mmpd_data) {
- ext4_warning(sb, "not enough memory for mmpd_data");
- goto failed;
- }
- mmpd_data->sb = sb;
- mmpd_data->bh = bh;
+ EXT4_SB(sb)->s_mmp_bh = bh;

/*
* Start a kernel thread to update the MMP block periodically.
*/
- EXT4_SB(sb)->s_mmp_tsk = kthread_run(kmmpd, mmpd_data, "kmmpd-%.*s",
+ EXT4_SB(sb)->s_mmp_tsk = kthread_run(kmmpd, sb, "kmmpd-%.*s",
(int)sizeof(mmp->mmp_bdevname),
bdevname(bh->b_bdev,
mmp->mmp_bdevname));
if (IS_ERR(EXT4_SB(sb)->s_mmp_tsk)) {
EXT4_SB(sb)->s_mmp_tsk = NULL;
- kfree(mmpd_data);
ext4_warning(sb, "Unable to create kmmpd thread for %s.",
sb->s_id);
goto failed;
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index d29f6aa7d96e..b6fe1a027c78 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1245,8 +1245,8 @@ static void ext4_put_super(struct super_block *sb)
ext4_xattr_destroy_cache(sbi->s_ea_block_cache);
sbi->s_ea_block_cache = NULL;

- if (sbi->s_mmp_tsk)
- kthread_stop(sbi->s_mmp_tsk);
+ ext4_stop_mmpd(sbi);
+
brelse(sbi->s_sbh);
sb->s_fs_info = NULL;
/*
@@ -5186,8 +5186,7 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
failed_mount3:
flush_work(&sbi->s_error_work);
del_timer_sync(&sbi->s_err_report);
- if (sbi->s_mmp_tsk)
- kthread_stop(sbi->s_mmp_tsk);
+ ext4_stop_mmpd(sbi);
failed_mount2:
rcu_read_lock();
group_desc = rcu_dereference(sbi->s_group_desc);
@@ -5989,8 +5988,7 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data)
*/
ext4_mark_recovery_complete(sb, es);
}
- if (sbi->s_mmp_tsk)
- kthread_stop(sbi->s_mmp_tsk);
+ ext4_stop_mmpd(sbi);
} else {
/* Make sure we can mount this feature set readwrite */
if (ext4_has_feature_readonly(sb) ||
--
2.30.2