Wind River Support Network

Description

In the Linux kernel, the following vulnerability has been resolved:  net: wan: farsync: Fix use-after-free bugs caused by unfinished tasklets  When the FarSync T-series card is being detached, the fst_card_info is deallocated in fst_remove_one(). However, the fst_tx_task or fst_int_task may still be running or pending, leading to use-after-free bugs when the already freed fst_card_info is accessed in fst_process_tx_work_q() or fst_process_int_work_q().  A typical race condition is depicted below:  CPU 0 (cleanup)           | CPU 1 (tasklet)                           | fst_start_xmit() fst_remove_one()          |   tasklet_schedule()   unregister_hdlc_device()|                           | fst_process_tx_work_q() //handler   kfree(card) //free      |   do_bottom_half_tx()                           |     card-> //use  The following KASAN trace was captured:  ==================================================================  BUG: KASAN: slab-use-after-free in do_bottom_half_tx+0xb88/0xd00  Read of size 4 at addr ffff88800aad101c by task ksoftirqd/3/32  ...  Call Trace:   <IRQ>   dump_stack_lvl+0x55/0x70   print_report+0xcb/0x5d0   ? do_bottom_half_tx+0xb88/0xd00   kasan_report+0xb8/0xf0   ? do_bottom_half_tx+0xb88/0xd00   do_bottom_half_tx+0xb88/0xd00   ? _raw_spin_lock_irqsave+0x85/0xe0   ? __pfx__raw_spin_lock_irqsave+0x10/0x10   ? __pfx___hrtimer_run_queues+0x10/0x10   fst_process_tx_work_q+0x67/0x90   tasklet_action_common+0x1fa/0x720   ? hrtimer_interrupt+0x31f/0x780   handle_softirqs+0x176/0x530   __irq_exit_rcu+0xab/0xe0   sysvec_apic_timer_interrupt+0x70/0x80  ...   Allocated by task 41 on cpu 3 at 72.330843s:   kasan_save_stack+0x24/0x50   kasan_save_track+0x17/0x60   __kasan_kmalloc+0x7f/0x90   fst_add_one+0x1a5/0x1cd0   local_pci_probe+0xdd/0x190   pci_device_probe+0x341/0x480   really_probe+0x1c6/0x6a0   __driver_probe_device+0x248/0x310   driver_probe_device+0x48/0x210   __device_attach_driver+0x160/0x320   bus_for_each_drv+0x101/0x190   __device_attach+0x198/0x3a0   device_initial_probe+0x78/0xa0   pci_bus_add_device+0x81/0xc0   pci_bus_add_devices+0x7e/0x190   enable_slot+0x9b9/0x1130   acpiphp_check_bridge.part.0+0x2e1/0x460   acpiphp_hotplug_notify+0x36c/0x3c0   acpi_device_hotplug+0x203/0xb10   acpi_hotplug_work_fn+0x59/0x80  ...   Freed by task 41 on cpu 1 at 75.138639s:   kasan_save_stack+0x24/0x50   kasan_save_track+0x17/0x60   kasan_save_free_info+0x3b/0x60   __kasan_slab_free+0x43/0x70   kfree+0x135/0x410   fst_remove_one+0x2ca/0x540   pci_device_remove+0xa6/0x1d0   device_release_driver_internal+0x364/0x530   pci_stop_bus_device+0x105/0x150   pci_stop_and_remove_bus_device+0xd/0x20   disable_slot+0x116/0x260   acpiphp_disable_and_eject_slot+0x4b/0x190   acpiphp_hotplug_notify+0x230/0x3c0   acpi_device_hotplug+0x203/0xb10   acpi_hotplug_work_fn+0x59/0x80  ...   The buggy address belongs to the object at ffff88800aad1000   which belongs to the cache kmalloc-1k of size 1024  The buggy address is located 28 bytes inside of   freed 1024-byte region  The buggy address belongs to the physical page:  page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0xaad0  head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0  flags: 0x100000000000040(head|node=0|zone=1)  page_type: f5(slab)  raw: 0100000000000040 ffff888007042dc0 dead000000000122 0000000000000000  raw: 0000000000000000 0000000080100010 00000000f5000000 0000000000000000  head: 0100000000000040 ffff888007042dc0 dead000000000122 0000000000000000  head: 0000000000000000 0000000080100010 00000000f5000000 0000000000000000  head: 0100000000000003 ffffea00002ab401 00000000ffffffff 00000000ffffffff  head: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000  page dumped because: kasan: bad access detected   Memory state around the buggy address:   ffff88800aad0f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc   ffff88800aad0f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc  >ffff88800aad1000: fa fb ---truncated---