Messages in this thread Patch in this message |  | | From | Mehdi Ben Hadj Khelifa <> | | Subject | [PATCH v2] fs/hfs: fix s_fs_info leak on setup_bdev_super() failure | | Date | Wed, 19 Nov 2025 08:38:20 +0100 |
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The regression introduced by commit aca740cecbe5 ("fs: open block device after superblock creation") allows setup_bdev_super() to fail after a new superblock has been allocated by sget_fc(), but before hfs_fill_super() takes ownership of the filesystem-specific s_fs_info data.
In that case, hfs_put_super() and the failure paths of hfs_fill_super() are never reached, leaving the HFS mdb structures attached to s->s_fs_info unreleased.The default kill_block_super() teardown also does not free HFS-specific resources, resulting in a memory leak on early mount failure.
Fix this by moving all HFS-specific teardown (hfs_mdb_put()) from hfs_put_super() and the hfs_fill_super() failure path into a dedicated hfs_kill_sb() implementation. This ensures that both normal unmount and early teardown paths (including setup_bdev_super() failure) correctly release HFS metadata.
This also preserves the intended layering: generic_shutdown_super() handles VFS-side cleanup, while HFS filesystem state is fully destroyed afterwards.
Fixes: aca740cecbe5 ("fs: open block device after superblock creation") Reported-by: syzbot+ad45f827c88778ff7df6@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=ad45f827c88778ff7df6 Tested-by: syzbot+ad45f827c88778ff7df6@syzkaller.appspotmail.com Suggested-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Mehdi Ben Hadj Khelifa <mehdi.benhadjkhelifa@gmail.com> --- ChangeLog:
Changes from v1:
-Changed the patch direction to focus on hfs changes specifically as suggested by al viro
Link:https://lore.kernel.org/all/20251114165255.101361-1-mehdi.benhadjkhelifa@gmail.com/
Note:This patch might need some more testing as I only did run selftests with no regression, check dmesg output for no regression, run reproducer with no bug and test it with syzbot as well.
fs/hfs/super.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-)
diff --git a/fs/hfs/super.c b/fs/hfs/super.c index 47f50fa555a4..06e1c25e47dc 100644 --- a/fs/hfs/super.c +++ b/fs/hfs/super.c @@ -49,8 +49,6 @@ static void hfs_put_super(struct super_block *sb) { cancel_delayed_work_sync(&HFS_SB(sb)->mdb_work); hfs_mdb_close(sb); - /* release the MDB's resources */ - hfs_mdb_put(sb); } static void flush_mdb(struct work_struct *work) @@ -383,7 +381,6 @@ static int hfs_fill_super(struct super_block *sb, struct fs_context *fc) bail_no_root: pr_err("get root inode failed\n"); bail: - hfs_mdb_put(sb); return res; } @@ -431,10 +428,21 @@ static int hfs_init_fs_context(struct fs_context *fc) return 0; } +static void hfs_kill_sb(struct super_block *sb) +{ + generic_shutdown_super(sb); + hfs_mdb_put(sb); + if (sb->s_bdev) { + sync_blockdev(sb->s_bdev); + bdev_fput(sb->s_bdev_file); + } + +} + static struct file_system_type hfs_fs_type = { .owner = THIS_MODULE, .name = "hfs", - .kill_sb = kill_block_super, + .kill_sb = hfs_kill_sb, .fs_flags = FS_REQUIRES_DEV, .init_fs_context = hfs_init_fs_context, }; -- 2.52.0
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