FKIE_CVE-2026-43232
Vulnerability from fkie_nvd - Published: 2026-05-06 12:16 - Updated: 2026-05-12 19:08
Severity ?
Summary
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---
References
Impacted products
| Vendor | Product | Version | |
|---|---|---|---|
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | 7.0 |
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"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "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": "CVE-2026-43232",
"lastModified": "2026-05-12T19:08:04.757",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "HIGH",
"baseScore": 8.8,
"baseSeverity": "HIGH",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "REQUIRED",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"exploitabilityScore": 2.8,
"impactScore": 5.9,
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"type": "Secondary"
}
]
},
"published": "2026-05-06T12:16:43.223",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"tags": [
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],
"url": "https://git.kernel.org/stable/c/04edfdfdfcdefc02408ab670607261b0a0a9a02e"
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},
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}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Analyzed",
"weaknesses": [
{
"description": [
{
"lang": "en",
"value": "CWE-416"
}
],
"source": "nvd@nist.gov",
"type": "Primary"
}
]
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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