In the Linux kernel, the following vulnerability has been resolved:
binfmt_misc: restore write access when removing an entry
Registering an entry with the MISC_FMT_OPEN_FILE flag opens the interpreter via open_exec() which denies write access to it for as long as the entry exists. Removing the entry closes the interpreter file via filp_close() but never restores write access, leaving the inodes i_writecount permanently negative. Opening the interpreter for writing keeps failing with ETXTBSY long after the entry is gone until the inode is evicted from the inode cache.
Commit 90f601b497d7 (binfmt_misc: restore write access before closing files opened by open_exec()) fixed the same imbalance in the error path of bm_register_write() but the actual removal path has been leaking the write denial since the introduction of the flag.
Restore write access in put_binfmt_handler() before closing the interpreter file.