kernel/linux.git/drivers/net/wan/farsync.c, branch v6.12.80

net: wan: farsync: Fix use-after-free bugs caused by unfinished tasklets

2026-03-04T12:21:34+00:00

[ Upstream commit bae8a5d2e759da2e0cba33ab2080deee96a09373 ] 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: 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 fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88800aad1080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88800aad1100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== Fix this by ensuring that both fst_tx_task and fst_int_task are properly canceled before the fst_card_info is released. Add tasklet_kill() in fst_remove_one() to synchronize with any pending or running tasklets. Since unregister_hdlc_device() stops data transmission and reception, and fst_disable_intr() prevents further interrupts, it is appropriate to place tasklet_kill() after these calls. The bugs were identified through static analysis. To reproduce the issue and validate the fix, a FarSync T-series card was simulated in QEMU and delays(e.g., mdelay()) were introduced within the tasklet handler to increase the likelihood of triggering the race condition. Fixes: 2f623aaf9f31 ("net: farsync: Fix kmemleak when rmmods farsync") Signed-off-by: Duoming Zhou Reviewed-by: Jijie Shao Link: https://patch.msgid.link/20260219124637.72578-1-duoming@zju.edu.cn Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin

net: farsync: Fix kmemleak when rmmods farsync

2022-12-12T09:42:45+00:00

There are two memory leaks reported by kmemleak: unreferenced object 0xffff888114b20200 (size 128): comm "modprobe", pid 4846, jiffies 4295146524 (age 401.345s) hex dump (first 32 bytes): e0 62 57 09 81 88 ff ff e0 62 57 09 81 88 ff ff .bW......bW..... 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [] kmalloc_trace+0x22/0x60 [] __hw_addr_add_ex+0x198/0x6c0 [] dev_addr_init+0x13d/0x230 [] alloc_netdev_mqs+0x10d/0xe50 [] alloc_hdlcdev+0x2e/0x80 [] fst_add_one+0x601/0x10e0 [farsync] ... unreferenced object 0xffff88810b85b000 (size 1024): comm "modprobe", pid 4846, jiffies 4295146523 (age 401.346s) hex dump (first 32 bytes): 00 00 b0 02 00 c9 ff ff 00 70 0a 00 00 c9 ff ff .........p...... 00 00 00 f2 00 00 00 f3 0a 00 00 00 02 00 00 00 ................ backtrace: [] kmalloc_trace+0x22/0x60 [] fst_add_one+0x154/0x10e0 [farsync] [] local_pci_probe+0xd3/0x170 ... The root cause is traced to the netdev and fst_card_info are not freed when removes one fst in fst_remove_one(), which may trigger oom if repeated insmod and rmmod module. Fix it by adding free_netdev() and kfree() in fst_remove_one(), just as the operations on the error handling path in fst_add_one(). Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Li Zetao Reviewed-by: Jiri Pirko Signed-off-by: David S. Miller

net: split out ndo_siowandev ioctl

2021-07-27T19:11:45+00:00

In order to further reduce the scope of ndo_do_ioctl(), move out the SIOCWANDEV handling into a new network device operation function. Adjust the prototype to only pass the if_settings sub-structure in place of the ifreq, and remove the redundant 'cmd' argument in the process. Cc: Krzysztof Halasa Cc: "Jan \"Yenya\" Kasprzak" Cc: Kevin Curtis Cc: Zhao Qiang Cc: Martin Schiller Cc: Jiri Slaby Cc: linux-x25@vger.kernel.org Signed-off-by: Arnd Bergmann Signed-off-by: David S. Miller

wan: use ndo_siocdevprivate

2021-07-27T19:11:44+00:00

The wan drivers each support some custom SIOCDEVPRIVATE ioctls, plus the common SIOCWANDEV command. Split these so the ioctl callback only deals with SIOCWANDEV and the rest is handled by ndo_siocdevprivate. It might make sense to also split out SIOCWANDEV into a separate callback in order to eventually remove ndo_do_ioctl entirely. Cc: Krzysztof Halasa Cc: Kevin Curtis Signed-off-by: Arnd Bergmann Signed-off-by: David S. Miller

net: farsync: replace comparison to NULL with "fst_card_array[i]"

2021-06-08T19:04:05+00:00

According to the chackpatch.pl, comparison to NULL could be written "fst_card_array[i]". Signed-off-by: Peng Li Signed-off-by: Guangbin Huang Signed-off-by: David S. Miller

net: farsync: remove redundant return

2021-06-08T19:04:05+00:00

Void function return statements are not generally useful. Signed-off-by: Peng Li Signed-off-by: Guangbin Huang Signed-off-by: David S. Miller

net: farsync: fix the alignment issue

2021-06-08T19:04:05+00:00

Alignment should match open parenthesis. Signed-off-by: Peng Li Signed-off-by: Guangbin Huang Signed-off-by: David S. Miller

net: farsync: remove redundant parentheses

2021-06-08T19:04:05+00:00

Unnecessary parentheses around 'port->hwif == X21'. Signed-off-by: Peng Li Signed-off-by: Guangbin Huang Signed-off-by: David S. Miller

net: farsync: remove redundant spaces

2021-06-08T19:04:05+00:00

According to the chackpatch.pl, space prohibited between function name and open parenthesis '(', no space is necessary after a cast. Signed-off-by: Peng Li Signed-off-by: Guangbin Huang Signed-off-by: David S. Miller

net: farsync: remove redundant braces {}

2021-06-08T19:04:05+00:00

This patch removes redundant braces {}, to fix the checkpatch.pl warning: "braces {} are not necessary for single statement blocks". Signed-off-by: Peng Li Signed-off-by: Guangbin Huang Signed-off-by: David S. Miller