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