CVE-2024-42271

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> net/iucv: fix use after free in iucv_sock_close()<br /> <br /> iucv_sever_path() is called from process context and from bh context.<br /> iucv-&gt;path is used as indicator whether somebody else is taking care of<br /> severing the path (or it is already removed / never existed).<br /> This needs to be done with atomic compare and swap, otherwise there is a<br /> small window where iucv_sock_close() will try to work with a path that has<br /> already been severed and freed by iucv_callback_connrej() called by<br /> iucv_tasklet_fn().<br /> <br /> Example:<br /> [452744.123844] Call Trace:<br /> [452744.123845] ([] 0x1e87f03880)<br /> [452744.123966] [] iucv_path_sever+0x96/0x138<br /> [452744.124330] [] iucv_sever_path+0xc2/0xd0 [af_iucv]<br /> [452744.124336] [] iucv_sock_close+0xa6/0x310 [af_iucv]<br /> [452744.124341] [] iucv_sock_release+0x3c/0xd0 [af_iucv]<br /> [452744.124345] [] __sock_release+0x5e/0xe8<br /> [452744.124815] [] sock_close+0x34/0x48<br /> [452744.124820] [] __fput+0xba/0x268<br /> [452744.124826] [] task_work_run+0xbc/0xf0<br /> [452744.124832] [] do_notify_resume+0x88/0x90<br /> [452744.124841] [] system_call+0xe2/0x2c8<br /> [452744.125319] Last Breaking-Event-Address:<br /> [452744.125321] [] iucv_path_sever+0x90/0x138<br /> [452744.125324]<br /> [452744.125325] Kernel panic - not syncing: Fatal exception in interrupt<br /> <br /> Note that bh_lock_sock() is not serializing the tasklet context against<br /> process context, because the check for sock_owned_by_user() and<br /> corresponding handling is missing.<br /> <br /> Ideas for a future clean-up patch:<br /> A) Correct usage of bh_lock_sock() in tasklet context, as described in<br /> Re-enqueue, if needed. This may require adding return values to the<br /> tasklet functions and thus changes to all users of iucv.<br /> <br /> B) Change iucv tasklet into worker and use only lock_sock() in af_iucv.