AZL-96344

In the Linux kernel, the following vulnerability has been resolved:

binfmt_misc: restore write access when removing an entry

Registering an entry with the MISCFMTOPENFILE flag opens the interpreter via openexec() which denies write access to it for as long as the entry exists. Removing the entry closes the interpreter file via filpclose() but never restores write access, leaving the inode's iwritecount 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 ("binfmtmisc: restore write access before closing files opened by openexec()") fixed the same imbalance in the error path of bmregisterwrite() but the actual removal path has been leaking the write denial since the introduction of the flag.

Restore write access in putbinfmthandler() before closing the interpreter file.