Re: [PATCH RFC 01/28] ecryptfs: don't leak the inode when a lookup can't open the lower file

[sashiko-bot@kernel.org]

> ecryptfs_lookup_interpose() opens the lower file of a regular file to
> read the size from the header. If that fails it calls make_bad_inode()
> and returns the error. A new inode is still I_NEW at that point and
> nothing ever unlocks or puts it, so it leaks together with the reference
> it holds on the lower inode. And an inode that was already in the cache
> gets marked bad for all its other users instead of just losing the
> reference this lookup took.
> 
> umount then complains:
> 
>   VFS: Busy inodes after unmount of ecryptfs (ecryptfs)
> 
> That's a WARN, or a BUG with CONFIG_BUG_ON_DATA_CORRUPTION. The lower
> filesystem reports the same when it is unmounted. Use iget_failed() for
> a new inode and iput() for one from the cache.
> 
> Reproducer, opening the lower file read-write fails on a read-only bind
> mount:
> 
>   sig=$(printf x | ecryptfs-add-passphrase - | sed -n 's/.*\[\(.*\)\].*/\1/p')
>   mount --bind -o ro /lower /lower
>   mount -i -t ecryptfs -o ecryptfs_sig=$sig,ecryptfs_cipher=aes,ecryptfs_key_bytes=16,ecryptfs_passthrough /lower /upper
>   cat /upper/f      # EROFS
>   umount /upper     # VFS: Busy inodes after unmount of ecryptfs
> 
> Fixes: 3b06b3ebf441 ("eCryptfs: Fix new inode race condition")
> Cc: stable@vger.kernel.org
> Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>

Sashiko has reviewed this patch and found no issues. It looks great!

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Sashiko AI review · https://sashiko.dev/#/patchset/20261012-work-fs-sb_rdonly-v1-0-60743a3dc326@kernel.org?part=1