5.4-stable review patch. If anyone has any objections, please let me know.
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From: Dmitry Antipov dmantipov@yandex.ru
commit a6aeb739974ec73e5217c75a7c008a688d3d5cf1 upstream.
In 'lookup_or_create_module_kobject()', an internal kobject is created using 'module_ktype'. So call to 'kobject_put()' on error handling path causes an attempt to use an uninitialized completion pointer in 'module_kobject_release()'. In this scenario, we just want to release kobject without an extra synchronization required for a regular module unloading process, so adding an extra check whether 'complete()' is actually required makes 'kobject_put()' safe.
Reported-by: syzbot+7fb8a372e1f6add936dd@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=7fb8a372e1f6add936dd Fixes: 942e443127e9 ("module: Fix mod->mkobj.kobj potentially freed too early") Cc: stable@vger.kernel.org Suggested-by: Petr Pavlu petr.pavlu@suse.com Signed-off-by: Dmitry Antipov dmantipov@yandex.ru Link: https://lore.kernel.org/r/20250507065044.86529-1-dmantipov@yandex.ru Signed-off-by: Petr Pavlu petr.pavlu@suse.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/params.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
--- a/kernel/params.c +++ b/kernel/params.c @@ -946,7 +946,9 @@ int module_sysfs_initialized; static void module_kobj_release(struct kobject *kobj) { struct module_kobject *mk = to_module_kobject(kobj); - complete(mk->kobj_completion); + + if (mk->kobj_completion) + complete(mk->kobj_completion); }
struct kobj_type module_ktype = {