From: Ryusuke Konishi konishi.ryusuke@gmail.com
commit 42560f9c92cc43dce75dbf06cc0d840dced39b12 upstream.
The current nilfs2 sysfs support has issues with the timing of creation and deletion of sysfs entries, potentially leading to null pointer dereferences, use-after-free, and lockdep warnings.
Some of the sysfs attributes for nilfs2 per-filesystem instance refer to metadata file "cpfile", "sufile", or "dat", but nilfs_sysfs_create_device_group that creates those attributes is executed before the inodes for these metadata files are loaded, and nilfs_sysfs_delete_device_group which deletes these sysfs entries is called after releasing their metadata file inodes.
Therefore, access to some of these sysfs attributes may occur outside of the lifetime of these metadata files, resulting in inode NULL pointer dereferences or use-after-free.
In addition, the call to nilfs_sysfs_create_device_group() is made during the locking period of the semaphore "ns_sem" of nilfs object, so the shrinker call caused by the memory allocation for the sysfs entries, may derive lock dependencies "ns_sem" -> (shrinker) -> "locks acquired in nilfs_evict_inode()".
Since nilfs2 may acquire "ns_sem" deep in the call stack holding other locks via its error handler __nilfs_error(), this causes lockdep to report circular locking. This is a false positive and no circular locking actually occurs as no inodes exist yet when nilfs_sysfs_create_device_group() is called. Fortunately, the lockdep warnings can be resolved by simply moving the call to nilfs_sysfs_create_device_group() out of "ns_sem".
This fixes these sysfs issues by revising where the device's sysfs interface is created/deleted and keeping its lifetime within the lifetime of the metadata files above.
Link: https://lkml.kernel.org/r/20230330205515.6167-1-konishi.ryusuke@gmail.com Fixes: dd70edbde262 ("nilfs2: integrate sysfs support into driver") Signed-off-by: Ryusuke Konishi konishi.ryusuke@gmail.com Reported-by: syzbot+979fa7f9c0d086fdc282@syzkaller.appspotmail.com Link: https://lkml.kernel.org/r/0000000000003414b505f7885f7e@google.com Reported-by: syzbot+5b7d542076d9bddc3c6a@syzkaller.appspotmail.com Link: https://lkml.kernel.org/r/0000000000006ac86605f5f44eb9@google.com Cc: Viacheslav Dubeyko slava@dubeyko.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/nilfs2/super.c | 2 ++ fs/nilfs2/the_nilfs.c | 12 +++++++----- 2 files changed, 9 insertions(+), 5 deletions(-)
--- a/fs/nilfs2/super.c +++ b/fs/nilfs2/super.c @@ -477,6 +477,7 @@ static void nilfs_put_super(struct super up_write(&nilfs->ns_sem); }
+ nilfs_sysfs_delete_device_group(nilfs); iput(nilfs->ns_sufile); iput(nilfs->ns_cpfile); iput(nilfs->ns_dat); @@ -1103,6 +1104,7 @@ nilfs_fill_super(struct super_block *sb, nilfs_put_root(fsroot);
failed_unload: + nilfs_sysfs_delete_device_group(nilfs); iput(nilfs->ns_sufile); iput(nilfs->ns_cpfile); iput(nilfs->ns_dat); --- a/fs/nilfs2/the_nilfs.c +++ b/fs/nilfs2/the_nilfs.c @@ -87,7 +87,6 @@ void destroy_nilfs(struct the_nilfs *nil { might_sleep(); if (nilfs_init(nilfs)) { - nilfs_sysfs_delete_device_group(nilfs); brelse(nilfs->ns_sbh[0]); brelse(nilfs->ns_sbh[1]); } @@ -275,6 +274,10 @@ int load_nilfs(struct the_nilfs *nilfs, goto failed; }
+ err = nilfs_sysfs_create_device_group(sb); + if (unlikely(err)) + goto sysfs_error; + if (valid_fs) goto skip_recovery;
@@ -336,6 +339,9 @@ int load_nilfs(struct the_nilfs *nilfs, goto failed;
failed_unload: + nilfs_sysfs_delete_device_group(nilfs); + + sysfs_error: iput(nilfs->ns_cpfile); iput(nilfs->ns_sufile); iput(nilfs->ns_dat); @@ -668,10 +674,6 @@ int init_nilfs(struct the_nilfs *nilfs, if (err) goto failed_sbh;
- err = nilfs_sysfs_create_device_group(sb); - if (err) - goto failed_sbh; - set_nilfs_init(nilfs); err = 0; out: