In the Linux kernel, the following vulnerability has been resolved:
smb: client: use finish_no_open() for non-regular inodes
An O_CREAT open can find an existing symlink or another non-regular
inode. cifs_atomic_open() calls finish_open() on it and attaches a
cifsFileInfo. Symlink inodes have no CIFS release operation, so the
dentry reference held by cifsFileInfo is leaked. FMODE_OPENED also
prevents the VFS from following the symlink.
Track whether cifs_do_create() returned an open server handle. For
non-regular inodes, close the handle if present, remove the pending
open, and call finish_no_open() so the VFS can continue the lookup.
Do not set FMODE_CREATED unless a regular file was opened. For
O_NOFOLLOW with __O_REGULAR, return -ELOOP before the VFS’s
-EFTYPE check.
Defer closing a legacy POSIX handle on a non-regular inode until
after inode lookup. This avoids closing it again if lookup fails.
