CVE-2024-26895: In the Linux kernel, the following vulnerability has been resolved:  wifi: wilc1000: prevent use-after-free on vif when cleaning up all interfaces  wilc_netdev_cleanup currently triggers a KASAN warning, which can be observed on interface registration error path, or simply by removing the module/unbinding device from driver:  echo spi0.1 > /sys/bus/spi/drivers/wilc1000_spi/unbind  ================================================================== BUG: KASAN: slab-use-after-free in wilc_netdev_cleanup+0x508/0x5cc Read of size 4 at addr c54d1ce8 by task sh/86  CPU: 0 PID: 86 Comm: sh Not tainted 6.8.0-rc1+ #117 Hardware name: Atmel SAMA5  unwind_backtrace from show_stack+0x18/0x1c  show_stack from dump_stack_lvl+0x34/0x58  dump_stack_lvl from print_report+0x154/0x500  print_report from kasan_report+0xac/0xd8  kasan_report from wilc_netdev_cleanup+0x508/0x5cc  wilc_netdev_cleanup from wilc_bus_remove+0xc8/0xec  wilc_bus_remove from spi_remove+0x8c/0xac  spi_remove from device_release_driver_internal+0x434/0x5f8  device_release_driver_internal from unbind_store+0xbc/0x108  unbind_store from kernfs_fop_write_iter+0x398/0x584  kernfs_fop_write_iter from vfs_write+0x728/0xf88  vfs_write from ksys_write+0x110/0x1e4  ksys_write from ret_fast_syscall+0x0/0x1c  [...]  Allocated by task 1:  kasan_save_track+0x30/0x5c  __kasan_kmalloc+0x8c/0x94  __kmalloc_node+0x1cc/0x3e4  kvmalloc_node+0x48/0x180  alloc_netdev_mqs+0x68/0x11dc  alloc_etherdev_mqs+0x28/0x34  wilc_netdev_ifc_init+0x34/0x8ec  wilc_cfg80211_init+0x690/0x910  wilc_bus_probe+0xe0/0x4a0  spi_probe+0x158/0x1b0  really_probe+0x270/0xdf4  __driver_probe_device+0x1dc/0x580  driver_probe_device+0x60/0x140  __driver_attach+0x228/0x5d4  bus_for_each_dev+0x13c/0x1a8  bus_add_driver+0x2a0/0x608  driver_register+0x24c/0x578  do_one_initcall+0x180/0x310  kernel_init_freeable+0x424/0x484  kernel_init+0x20/0x148  ret_from_fork+0x14/0x28  Freed by task 86:  kasan_save_track+0x30/0x5c  kasan_save_free_info+0x38/0x58  __kasan_slab_free+0xe4/0x140  kfree+0xb0/0x238  device_release+0xc0/0x2a8  kobject_put+0x1d4/0x46c  netdev_run_todo+0x8fc/0x11d0  wilc_netdev_cleanup+0x1e4/0x5cc  wilc_bus_remove+0xc8/0xec  spi_remove+0x8c/0xac  device_release_driver_internal+0x434/0x5f8  unbind_store+0xbc/0x108  kernfs_fop_write_iter+0x398/0x584  vfs_write+0x728/0xf88  ksys_write+0x110/0x1e4  ret_fast_syscall+0x0/0x1c  [...]  David Mosberger-Tan initial investigation [1] showed that this use-after-free is due to netdevice unregistration during vif list traversal. When unregistering a net device, since the needs_free_netdev has been set to true during registration, the netdevice object is also freed, and as a consequence, the corresponding vif object too, since it is attached to it as private netdevice data. The next occurrence of the loop then tries to access freed vif pointer to the list to move forward in the list.  Fix this use-after-free thanks to two mechanisms: - navigate in the list with list_for_each_entry_safe, which allows to   safely modify the list as we go through each element. For each element,   remove it from the list with list_del_rcu - make sure to wait for RCU grace period end after each vif removal to make   sure it is safe to free the corresponding vif too (through   unregister_netdev)  Since we are in a RCU "modifier" path (not a "reader" path), and because such path is expected not to be concurrent to any other modifier (we are using the vif_mutex lock), we do not need to use RCU list API, that's why we can benefit from list_for_each_entry_safe.  [1] https://lore.kernel.org/linux-wireless/ab077dbe58b1ea5de0a3b2ca21f275a07af967d2.camel@egauge.net/