KASAN: slab-use-after-free Read in __setup_irq

Status: upstream: reported on 2026/09/23 23:13
Subsystems: kernel
Labels: prio:high
[Documentation on labels]
Reported-by: syzbot+843bf2f48f4d12e6682e@syzkaller.appspotmail.com
First crash: 44d, last: 14h50m
▶ ▼ ✨ AI Jobs (4)
ID Workflow Result Correct Bug Created Started Finished Revision
d8c84012 repro-c 💥 KASAN: slab-use-after-free Read in __setup_irq 2026/08/15 11:44 2026/08/15 11:44 2026/08/15 18:28 746171ee
ac9b0e08 moderation Actionable: ❌ ❓ KASAN: slab-use-after-free Read in __setup_irq 2026/08/15 00:01 2026/08/15 00:01 2026/08/15 00:03 746171ee
64a25f2f repro-c 💥 KASAN: slab-use-after-free Read in __setup_irq 2026/08/14 15:13 2026/08/14 15:13 2026/08/14 22:52 746171ee
07a59ca5 assessment-security DenialOfService: ✅ Exploitable: ✅ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ✅ UserNamespace: ✅ VMGuestTrigger: ✅ VMHostTrigger: ❌ ❓ KASAN: slab-use-after-free Read in __setup_irq 2026/08/12 03:28 2026/08/12 03:28 2026/08/12 04:14 f8d35649
▶ ▼ Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [kernel?] KASAN: slab-use-after-free Read in __setup_irq 0 (1) 2026/09/23 23:13
▶ ▼ Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.6 KASAN: slab-use-after-free Read in __setup_irq 19 1 1d11h 1d11h 0/2 upstream: reported on 2026/09/23 02:54

Sample crash report:
==================================================================
BUG: KASAN: slab-use-after-free in string_nocheck lib/vsprintf.c:648 [inline]
BUG: KASAN: slab-use-after-free in string+0x471/0x4d0 lib/vsprintf.c:730
Read of size 1 at addr ffff88802643b8a0 by task syz.0.818/8415

CPU: 1 UID: 0 PID: 8415 Comm: syz.0.818 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2026
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0x13d/0x4b0 mm/kasan/report.c:482
 kasan_report+0xdf/0x1c0 mm/kasan/report.c:595
 string_nocheck lib/vsprintf.c:648 [inline]
 string+0x471/0x4d0 lib/vsprintf.c:730
 vsnprintf+0x422/0x1300 lib/vsprintf.c:2949
 vprintk_store+0x3b3/0xbe0 kernel/printk/printk.c:2307
 vprintk_emit+0x139/0x6b0 kernel/printk/printk.c:2455
 _printk+0xcf/0x110 kernel/printk/printk.c:2504
 __setup_irq.cold+0x3be/0x3f1 kernel/irq/manage.c:1821
 request_threaded_irq+0x261/0x3e0 kernel/irq/manage.c:2184
 request_irq include/linux/interrupt.h:176 [inline]
 pcl812_attach+0x1b62/0x2300 drivers/comedi/drivers/pcl812.c:1174
 comedi_device_attach+0x40e/0x6b0 drivers/comedi/drivers.c:1101
 do_devconfig_ioctl+0x1b3/0x6d0 drivers/comedi/comedi_fops.c:930
 comedi_unlocked_ioctl+0x860/0x3310 drivers/comedi/comedi_fops.c:2302
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl fs/ioctl.c:583 [inline]
 __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fcaa579e159
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fcaa6663028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fcaa5a25fa0 RCX: 00007fcaa579e159
RDX: 0000200000000240 RSI: 0000000040946400 RDI: 0000000000000006
RBP: 00007fcaa583506b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fcaa5a26038 R14: 00007fcaa5a25fa0 R15: 00007fffa588bd58
 </TASK>

Allocated by task 1:
 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
 kasan_save_track+0x14/0x30 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __do_kmalloc_node mm/slub.c:5414 [inline]
 __kmalloc_node_track_caller_noprof+0x33d/0x870 mm/slub.c:5545
 kvasprintf+0xbc/0x150 lib/kasprintf.c:25
 kasprintf+0xc7/0x100 lib/kasprintf.c:59
 serial_core_add_one_port drivers/tty/serial/serial_core.c:3106 [inline]
 serial_core_register_port+0x46b/0x1660 drivers/tty/serial/serial_core.c:3353
 serial8250_register_8250_port+0x16c7/0x2440 drivers/tty/serial/8250/8250_core.c:877
 serial_pnp_probe+0x443/0x950 drivers/tty/serial/8250/8250_pnp.c:480
 pnp_device_probe+0x2b3/0x4a0 drivers/pnp/driver.c:111
 call_driver_probe drivers/base/dd.c:628 [inline]
 really_probe+0x241/0xa60 drivers/base/dd.c:706
 __driver_probe_device+0x210/0x460 drivers/base/dd.c:868
 driver_probe_device+0x4a/0x140 drivers/base/dd.c:898
 __driver_attach+0x21f/0x5b0 drivers/base/dd.c:1292
 bus_for_each_dev+0x13e/0x1d0 drivers/base/bus.c:383
 bus_add_driver+0x305/0x5b0 drivers/base/bus.c:763
 driver_register+0x1e2/0x360 drivers/base/driver.c:174
 serial8250_init+0xcc/0x1c0 drivers/tty/serial/8250/8250_platform.c:318
 do_one_initcall+0x11c/0x6f0 init/main.c:1362
 do_initcall_level init/main.c:1424 [inline]
 do_initcalls init/main.c:1440 [inline]
 do_basic_setup init/main.c:1460 [inline]
 kernel_init_freeable+0x6ea/0x7b0 init/main.c:1675
 kernel_init+0x21/0x1e0 init/main.c:1565
 ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Freed by task 8240:
 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
 kasan_save_track+0x14/0x30 mm/kasan/common.c:78
 kasan_save_free_info+0x3b/0x70 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5f/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2748 [inline]
 slab_free mm/slub.c:6508 [inline]
 kfree+0x22b/0x6d0 mm/slub.c:6801
 serial_core_remove_one_port drivers/tty/serial/serial_core.c:3222 [inline]
 serial_core_unregister_port+0x4b9/0x960 drivers/tty/serial/serial_core.c:3383
 serial8250_unregister_port+0x1db/0x890 drivers/tty/serial/8250/8250_core.c:932
 pnp_device_remove+0x7f/0x250 drivers/pnp/driver.c:133
 device_remove+0xcb/0x180 drivers/base/dd.c:616
 __device_release_driver drivers/base/dd.c:1349 [inline]
 device_release_driver_internal+0x44e/0x620 drivers/base/dd.c:1372
 unbind_store+0xf8/0x110 drivers/base/bus.c:244
 drv_attr_store+0x74/0xb0 drivers/base/bus.c:125
 sysfs_kf_write+0xf2/0x150 fs/sysfs/file.c:145
 kernfs_fop_write_iter+0x3e0/0x5f0 fs/kernfs/file.c:345
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x6af/0x1050 fs/read_write.c:687
 ksys_write+0x12a/0x250 fs/read_write.c:739
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88802643b8a0
 which belongs to the cache kmalloc-8 of size 8
The buggy address is located 0 bytes inside of
 freed 8-byte region [ffff88802643b8a0, ffff88802643b8a8)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2643b
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000000 ffff88801c034500 dead000000000100 dead000000000122
raw: 0000000000000000 0000000000800080 00000000f5000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0xd2cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 4167969447
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0xfd/0x120 mm/page_alloc.c:1871
 prep_new_page mm/page_alloc.c:1879 [inline]
 get_page_from_freelist+0x110d/0x35d0 mm/page_alloc.c:3943
 __alloc_frozen_pages_noprof+0x2eb/0x3300 mm/page_alloc.c:5436
 alloc_slab_page mm/slub.c:3347 [inline]
 allocate_slab mm/slub.c:3462 [inline]
 new_slab+0xa9/0x6e0 mm/slub.c:3513
 refill_objects+0xe3/0x410 mm/slub.c:7417
 refill_sheaf mm/slub.c:2885 [inline]
 __pcs_replace_empty_main+0x35e/0x650 mm/slub.c:4774
 alloc_from_pcs mm/slub.c:4850 [inline]
 slab_alloc_node mm/slub.c:4984 [inline]
 __do_kmalloc_node mm/slub.c:5413 [inline]
 __kmalloc_node_track_caller_noprof+0x6a8/0x870 mm/slub.c:5545
 __kmemdup_nul mm/util.c:64 [inline]
 kstrdup+0x51/0xe0 mm/util.c:84
 kstrdup_const+0x63/0x80 mm/util.c:104
 kvasprintf_const+0x10f/0x1a0 lib/kasprintf.c:48
 kobject_set_name_vargs+0x5a/0x140 lib/kobject.c:274
 dev_set_name+0xc7/0x100 drivers/base/core.c:3564
 tty_register_device_attr+0x2fb/0x7f0 drivers/tty/tty_io.c:3230
 tty_register_device drivers/tty/tty_io.c:3171 [inline]
 tty_register_driver+0x769/0xb50 drivers/tty/tty_io.c:3449
 legacy_pty_init drivers/tty/pty.c:579 [inline]
 pty_init+0x65d/0xdc0 drivers/tty/pty.c:919
 do_one_initcall+0x11c/0x6f0 init/main.c:1362
page_owner free stack trace missing

Memory state around the buggy address:
 ffff88802643b780: 05 fc fc fc 05 fc fc fc 05 fc fc fc 05 fc fc fc
 ffff88802643b800: 05 fc fc fc 05 fc fc fc 05 fc fc fc 05 fc fc fc
>ffff88802643b880: 05 fc fc fc fa fc fc fc 05 fc fc fc fa fc fc fc
                               ^
 ffff88802643b900: fa fc fc fc 05 fc fc fc fa fc fc fc fa fc fc fc
 ffff88802643b980: fa fc fc fc 04 fc fc fc 00 fc fc fc 00 fc fc fc
==================================================================

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/09/23 23:12 upstream fe2ec83746e5 0a1606bc .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root KASAN: slab-use-after-free Read in __setup_irq
2026/09/23 21:03 upstream fe2ec83746e5 0a1606bc .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root KASAN: slab-use-after-free Read in __setup_irq
2026/09/23 21:03 upstream fe2ec83746e5 0a1606bc .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root KASAN: slab-use-after-free Read in __setup_irq
2026/08/11 16:14 upstream f5bbbfec59b4 557a89d3 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: slab-use-after-free Read in __setup_irq
2026/08/10 15:09 upstream db2ddb871435 558388e4 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: slab-use-after-free Read in __setup_irq
* Struck through repros no longer work on HEAD.