CVE-2026-74486

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

binfmt_misc: use exe_file_deny_write_access() for the interpreter clone

For MISC_FMT_OPEN_FILE entries load_misc_binary() clones the

registered interpreter file and denies write access to the clone via

plain deny_write_access(). The clone is installed as

bprm->interpreter and later released by the exec machinery through

exe_file_allow_write_access() which skips the i_writecount increment

for files with FMODE_FSNOTIFY_HSM set.

The deny and allow side can therefore come to different conclusions

when pre-content watches are in play: if a pre-content watch is added

to the interpreter after registration every subsequent exec through

that entry takes a write denial on the clone that is never paired

with a write allowance, driving the interpreter inode's i_writecount

further down with each exec and leaving the interpreter unwritable

even after the entry and all its users are gone.

Take the write denial via exe_file_deny_write_access() so both sides

of the pairing base their decision on the same file mode, and

propagate failure instead of silently ignoring it: an interpreter

that is concurrently open for writing now fails the exec with

ETXTBSY, exactly like an interpreter freshly opened via open_exec()

would.