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ext4: fix memory leak in ext4_fill_super

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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>
This commit is contained in:
Pavel Skripkin 2021-04-30 21:50:46 +03:00 • committed by Theodore Ts'o
parent 1fc57ca5a2
commit 618f003199
3 changed files with 21 additions and 21 deletions
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4
fs/ext4/ext4.h
View file

@ -1488,6 +1488,7 @@ struct ext4_sb_info {
struct kobject s_kobj; struct kobject s_kobj;
struct completion s_kobj_unregister; struct completion s_kobj_unregister;
struct super_block *s_sb; struct super_block *s_sb;
struct buffer_head *s_mmp_bh;
/* Journaling */ /* Journaling */
struct journal_s *s_journal; 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 */ /* mmp.c */
extern int ext4_multi_mount_protect(struct super_block *, ext4_fsblk_t); 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 */ /* verity.c */
extern const struct fsverity_operations ext4_verityops; extern const struct fsverity_operations ext4_verityops;

28
fs/ext4/mmp.c
View file

@ -127,9 +127,9 @@ void __dump_mmp_msg(struct super_block *sb, struct mmp_struct *mmp,
*/ */
static int kmmpd(void *data) static int kmmpd(void *data)
{ {
struct super_block *sb = ((struct mmpd_data *) data)->sb; struct super_block *sb = (struct super_block *) data;
struct buffer_head *bh = ((struct mmpd_data *) data)->bh;
struct ext4_super_block *es = EXT4_SB(sb)->s_es; struct ext4_super_block *es = EXT4_SB(sb)->s_es;
struct buffer_head *bh = EXT4_SB(sb)->s_mmp_bh;
struct mmp_struct *mmp; struct mmp_struct *mmp;
ext4_fsblk_t mmp_block; ext4_fsblk_t mmp_block;
u32 seq = 0; u32 seq = 0;
@ -245,12 +245,18 @@ static int kmmpd(void *data)
retval = write_mmp_block(sb, bh); retval = write_mmp_block(sb, bh);
exit_thread: exit_thread:
EXT4_SB(sb)->s_mmp_tsk = NULL;
kfree(data);
brelse(bh);
return retval; 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 * Get a random new sequence number but make sure it is not greater than
* EXT4_MMP_SEQ_MAX. * 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 ext4_super_block *es = EXT4_SB(sb)->s_es;
struct buffer_head *bh = NULL; struct buffer_head *bh = NULL;
struct mmp_struct *mmp = NULL; struct mmp_struct *mmp = NULL;
struct mmpd_data *mmpd_data;
u32 seq; u32 seq;
unsigned int mmp_check_interval = le16_to_cpu(es->s_mmp_update_interval); unsigned int mmp_check_interval = le16_to_cpu(es->s_mmp_update_interval);
unsigned int wait_time = 0; unsigned int wait_time = 0;
@ -364,24 +369,17 @@ skip:
goto failed; goto failed;
} }
mmpd_data = kmalloc(sizeof(*mmpd_data), GFP_KERNEL); EXT4_SB(sb)->s_mmp_bh = bh;
if (!mmpd_data) {
ext4_warning(sb, "not enough memory for mmpd_data");
goto failed;
}
mmpd_data->sb = sb;
mmpd_data->bh = bh;
/* /*
* Start a kernel thread to update the MMP block periodically. * 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), (int)sizeof(mmp->mmp_bdevname),
bdevname(bh->b_bdev, bdevname(bh->b_bdev,
mmp->mmp_bdevname)); mmp->mmp_bdevname));
if (IS_ERR(EXT4_SB(sb)->s_mmp_tsk)) { if (IS_ERR(EXT4_SB(sb)->s_mmp_tsk)) {
EXT4_SB(sb)->s_mmp_tsk = NULL; EXT4_SB(sb)->s_mmp_tsk = NULL;
kfree(mmpd_data);
ext4_warning(sb, "Unable to create kmmpd thread for %s.", ext4_warning(sb, "Unable to create kmmpd thread for %s.",
sb->s_id); sb->s_id);
goto failed; goto failed;

10
fs/ext4/super.c
View file

@ -1245,8 +1245,8 @@ static void ext4_put_super(struct super_block *sb)
ext4_xattr_destroy_cache(sbi->s_ea_block_cache); ext4_xattr_destroy_cache(sbi->s_ea_block_cache);
sbi->s_ea_block_cache = NULL; sbi->s_ea_block_cache = NULL;
if (sbi->s_mmp_tsk) ext4_stop_mmpd(sbi);
kthread_stop(sbi->s_mmp_tsk);
brelse(sbi->s_sbh); brelse(sbi->s_sbh);
sb->s_fs_info = NULL; sb->s_fs_info = NULL;
/* /*
@ -5186,8 +5186,7 @@ failed_mount3a:
failed_mount3: failed_mount3:
flush_work(&sbi->s_error_work); flush_work(&sbi->s_error_work);
del_timer_sync(&sbi->s_err_report); del_timer_sync(&sbi->s_err_report);
if (sbi->s_mmp_tsk) ext4_stop_mmpd(sbi);
kthread_stop(sbi->s_mmp_tsk);
failed_mount2: failed_mount2:
rcu_read_lock(); rcu_read_lock();
group_desc = rcu_dereference(sbi->s_group_desc); 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); ext4_mark_recovery_complete(sb, es);
} }
if (sbi->s_mmp_tsk) ext4_stop_mmpd(sbi);
kthread_stop(sbi->s_mmp_tsk);
} else { } else {
/* Make sure we can mount this feature set readwrite */ /* Make sure we can mount this feature set readwrite */
if (ext4_has_feature_readonly(sb) || if (ext4_has_feature_readonly(sb) ||