GHSA-84HG-9FJM-PCR7
Vulnerability from github – Published: 2026-05-06 12:30 – Updated: 2026-05-08 15:31In 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: 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 ? __pfxhrtimerrun_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---
{
"affected": [],
"aliases": [
"CVE-2026-43232"
],
"database_specific": {
"cwe_ids": [
"CWE-416"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-05-06T12:16:43Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: wan: farsync: Fix use-after-free bugs caused by unfinished tasklets\n\nWhen the FarSync T-series card is being detached, the fst_card_info is\ndeallocated in fst_remove_one(). However, the fst_tx_task or fst_int_task\nmay still be running or pending, leading to use-after-free bugs when the\nalready freed fst_card_info is accessed in fst_process_tx_work_q() or\nfst_process_int_work_q().\n\nA typical race condition is depicted below:\n\nCPU 0 (cleanup) | CPU 1 (tasklet)\n | fst_start_xmit()\nfst_remove_one() | tasklet_schedule()\n unregister_hdlc_device()|\n | fst_process_tx_work_q() //handler\n kfree(card) //free | do_bottom_half_tx()\n | card-\u003e //use\n\nThe following KASAN trace was captured:\n\n==================================================================\n BUG: KASAN: slab-use-after-free in do_bottom_half_tx+0xb88/0xd00\n Read of size 4 at addr ffff88800aad101c by task ksoftirqd/3/32\n ...\n Call Trace:\n \u003cIRQ\u003e\n dump_stack_lvl+0x55/0x70\n print_report+0xcb/0x5d0\n ? do_bottom_half_tx+0xb88/0xd00\n kasan_report+0xb8/0xf0\n ? do_bottom_half_tx+0xb88/0xd00\n do_bottom_half_tx+0xb88/0xd00\n ? _raw_spin_lock_irqsave+0x85/0xe0\n ? __pfx__raw_spin_lock_irqsave+0x10/0x10\n ? __pfx___hrtimer_run_queues+0x10/0x10\n fst_process_tx_work_q+0x67/0x90\n tasklet_action_common+0x1fa/0x720\n ? hrtimer_interrupt+0x31f/0x780\n handle_softirqs+0x176/0x530\n __irq_exit_rcu+0xab/0xe0\n sysvec_apic_timer_interrupt+0x70/0x80\n ...\n\n Allocated by task 41 on cpu 3 at 72.330843s:\n kasan_save_stack+0x24/0x50\n kasan_save_track+0x17/0x60\n __kasan_kmalloc+0x7f/0x90\n fst_add_one+0x1a5/0x1cd0\n local_pci_probe+0xdd/0x190\n pci_device_probe+0x341/0x480\n really_probe+0x1c6/0x6a0\n __driver_probe_device+0x248/0x310\n driver_probe_device+0x48/0x210\n __device_attach_driver+0x160/0x320\n bus_for_each_drv+0x101/0x190\n __device_attach+0x198/0x3a0\n device_initial_probe+0x78/0xa0\n pci_bus_add_device+0x81/0xc0\n pci_bus_add_devices+0x7e/0x190\n enable_slot+0x9b9/0x1130\n acpiphp_check_bridge.part.0+0x2e1/0x460\n acpiphp_hotplug_notify+0x36c/0x3c0\n acpi_device_hotplug+0x203/0xb10\n acpi_hotplug_work_fn+0x59/0x80\n ...\n\n Freed by task 41 on cpu 1 at 75.138639s:\n kasan_save_stack+0x24/0x50\n kasan_save_track+0x17/0x60\n kasan_save_free_info+0x3b/0x60\n __kasan_slab_free+0x43/0x70\n kfree+0x135/0x410\n fst_remove_one+0x2ca/0x540\n pci_device_remove+0xa6/0x1d0\n device_release_driver_internal+0x364/0x530\n pci_stop_bus_device+0x105/0x150\n pci_stop_and_remove_bus_device+0xd/0x20\n disable_slot+0x116/0x260\n acpiphp_disable_and_eject_slot+0x4b/0x190\n acpiphp_hotplug_notify+0x230/0x3c0\n acpi_device_hotplug+0x203/0xb10\n acpi_hotplug_work_fn+0x59/0x80\n ...\n\n The buggy address belongs to the object at ffff88800aad1000\n which belongs to the cache kmalloc-1k of size 1024\n The buggy address is located 28 bytes inside of\n freed 1024-byte region\n The buggy address belongs to the physical page:\n page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0xaad0\n head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0\n flags: 0x100000000000040(head|node=0|zone=1)\n page_type: f5(slab)\n raw: 0100000000000040 ffff888007042dc0 dead000000000122 0000000000000000\n raw: 0000000000000000 0000000080100010 00000000f5000000 0000000000000000\n head: 0100000000000040 ffff888007042dc0 dead000000000122 0000000000000000\n head: 0000000000000000 0000000080100010 00000000f5000000 0000000000000000\n head: 0100000000000003 ffffea00002ab401 00000000ffffffff 00000000ffffffff\n head: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000\n page dumped because: kasan: bad access detected\n\n Memory state around the buggy address:\n ffff88800aad0f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc\n ffff88800aad0f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc\n \u003effff88800aad1000: fa fb\n---truncated---",
"id": "GHSA-84hg-9fjm-pcr7",
"modified": "2026-05-08T15:31:18Z",
"published": "2026-05-06T12:30:34Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-43232"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/04edfdfdfcdefc02408ab670607261b0a0a9a02e"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/086131807d119238cd464e5b0845e48d938dfd79"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/200bdb8d367ca9b478f9c56ebe56411604d55c81"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/21d341fe514fd07e345ed264c9eee21cb2061ca2"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/337d7b4112a47984ee319171b75b73bab47e7924"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/ae894e47e1cd5a6bf8a0423d888c45df8b2b02dc"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/bae8a5d2e759da2e0cba33ab2080deee96a09373"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/cac048ebfbb92d91d719f74b59177cb70a7633b8"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
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