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| author | Alexey Makhalov <amakhalov@vmware.com> | 2021-05-21 07:55:33 +0000 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2021-06-06 10:10:23 -0400 |
| commit | afd09b617db3786b6ef3dc43e28fe728cfea84df (patch) | |
| tree | 3e612dc22ab944ab65510703fbf47edfd77ce71c | |
| parent | a7ba36bc94f20b6c77f16364b9a23f582ea8faac (diff) | |
| download | linux-afd09b617db3786b6ef3dc43e28fe728cfea84df.tar.bz2 | |
ext4: fix memory leak in ext4_fill_super
Buffer head references must be released before calling kill_bdev();
otherwise the buffer head (and its page referenced by b_data) will not
be freed by kill_bdev, and subsequently that bh will be leaked.
If blocksizes differ, sb_set_blocksize() will kill current buffers and
page cache by using kill_bdev(). And then super block will be reread
again but using correct blocksize this time. sb_set_blocksize() didn't
fully free superblock page and buffer head, and being busy, they were
not freed and instead leaked.
This can easily be reproduced by calling an infinite loop of:
systemctl start <ext4_on_lvm>.mount, and
systemctl stop <ext4_on_lvm>.mount
... since systemd creates a cgroup for each slice which it mounts, and
the bh leak get amplified by a dying memory cgroup that also never
gets freed, and memory consumption is much more easily noticed.
Fixes: ce40733ce93d ("ext4: Check for return value from sb_set_blocksize")
Fixes: ac27a0ec112a ("ext4: initial copy of files from ext3")
Link: https://lore.kernel.org/r/20210521075533.95732-1-amakhalov@vmware.com
Signed-off-by: Alexey Makhalov <amakhalov@vmware.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org
| -rw-r--r-- | fs/ext4/super.c | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 886e0d518668..f66c7301b53a 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -4462,14 +4462,20 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent) } if (sb->s_blocksize != blocksize) { + /* + * bh must be released before kill_bdev(), otherwise + * it won't be freed and its page also. kill_bdev() + * is called by sb_set_blocksize(). + */ + brelse(bh); /* Validate the filesystem blocksize */ if (!sb_set_blocksize(sb, blocksize)) { ext4_msg(sb, KERN_ERR, "bad block size %d", blocksize); + bh = NULL; goto failed_mount; } - brelse(bh); logical_sb_block = sb_block * EXT4_MIN_BLOCK_SIZE; offset = do_div(logical_sb_block, blocksize); bh = ext4_sb_bread_unmovable(sb, logical_sb_block); @@ -5202,8 +5208,9 @@ failed_mount: kfree(get_qf_name(sb, sbi, i)); #endif fscrypt_free_dummy_policy(&sbi->s_dummy_enc_policy); - ext4_blkdev_remove(sbi); + /* ext4_blkdev_remove() calls kill_bdev(), release bh before it. */ brelse(bh); + ext4_blkdev_remove(sbi); out_fail: sb->s_fs_info = NULL; kfree(sbi->s_blockgroup_lock); |