syzbot

 sign-in | mailing list | source | docs
🐞 Open [1499]
≡ Subsystems
🐞 Fixed [6533]
🐞 Invalid [16701]
⬇ Missing Backports [202]
≡ Crashes
Kernel Health Bugs/Month Bug Lifetimes Fuzzing
Total Repo Heatmap Subsystems Heatmap
💬 Send us feedback

KASAN: slab-use-after-free Read in uart_write (2)

Status: moderation: reported on 2025/08/31 04:12
Subsystems: serial
[Documentation on labels]
Reported-by: syzbot+b5110677db52cf19e5e9@syzkaller.appspotmail.com
First crash: 6d06h, last: 6d06h
▶ ▼ Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: slab-use-after-free Read in uart_write serial 19 1 277d 273d 0/29 auto-obsoleted due to no activity on 2025/03/08 16:09

Sample crash report:
==================================================================
BUG: KASAN: slab-use-after-free in uart_write+0x53/0x130 drivers/tty/serial/serial_core.c:612
Read of size 8 at addr ffff88805b60b5f8 by task aoe_tx0/1302

CPU: 0 UID: 0 PID: 1302 Comm: aoe_tx0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xca/0x240 mm/kasan/report.c:482
 kasan_report+0x118/0x150 mm/kasan/report.c:595
 uart_write+0x53/0x130 drivers/tty/serial/serial_core.c:612
 handle_tx+0x23f/0x610 drivers/net/caif/caif_serial.c:222
 __netdev_start_xmit include/linux/netdevice.h:5222 [inline]
 netdev_start_xmit include/linux/netdevice.h:5231 [inline]
 xmit_one net/core/dev.c:3839 [inline]
 dev_hard_start_xmit+0x2d7/0x830 net/core/dev.c:3855
 __dev_queue_xmit+0x1b8d/0x3b50 net/core/dev.c:4725
 dev_queue_xmit include/linux/netdevice.h:3361 [inline]
 tx+0x6b/0x190 drivers/block/aoe/aoenet.c:62
 kthread+0x1cd/0x3e0 drivers/block/aoe/aoecmd.c:1241
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x47c/0x820 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Allocated by task 19669:
 kasan_save_stack mm/kasan/common.c:56 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:77
 poison_kmalloc_redzone mm/kasan/common.c:397 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:414
 kasan_kmalloc include/linux/kasan.h:260 [inline]
 __kmalloc_cache_noprof+0x21c/0x3a0 mm/slub.c:4396
 kmalloc_noprof include/linux/slab.h:909 [inline]
 kzalloc_noprof include/linux/slab.h:1043 [inline]
 alloc_tty_struct+0xa6/0x780 drivers/tty/tty_io.c:3102
 tty_init_dev+0x59/0x4d0 drivers/tty/tty_io.c:1400
 tty_open_by_driver drivers/tty/tty_io.c:2073 [inline]
 tty_open+0x5ab/0xd10 drivers/tty/tty_io.c:2120
 chrdev_open+0x4cc/0x5e0 fs/char_dev.c:414
 do_dentry_open+0x950/0x13f0 fs/open.c:965
 vfs_open+0x3b/0x340 fs/open.c:1095
 do_open fs/namei.c:3887 [inline]
 path_openat+0x2ee5/0x3830 fs/namei.c:4046
 do_filp_open+0x1fa/0x410 fs/namei.c:4073
 do_sys_openat2+0x121/0x1c0 fs/open.c:1435
 do_sys_open fs/open.c:1450 [inline]
 __do_sys_openat fs/open.c:1466 [inline]
 __se_sys_openat fs/open.c:1461 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1461
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 5900:
 kasan_save_stack mm/kasan/common.c:56 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:77
 __kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:587
 kasan_save_free_info mm/kasan/kasan.h:406 [inline]
 poison_slab_object mm/kasan/common.c:252 [inline]
 __kasan_slab_free+0x5b/0x80 mm/kasan/common.c:284
 kasan_slab_free include/linux/kasan.h:233 [inline]
 slab_free_hook mm/slub.c:2417 [inline]
 slab_free mm/slub.c:4680 [inline]
 kfree+0x18e/0x440 mm/slub.c:4879
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3319
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x47c/0x820 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Last potentially related work creation:
 kasan_save_stack+0x3e/0x60 mm/kasan/common.c:56
 kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:559
 insert_work+0x3d/0x330 kernel/workqueue.c:2184
 __queue_work+0xcd2/0xfb0 kernel/workqueue.c:2339
 queue_work_on+0x181/0x270 kernel/workqueue.c:2390
 tty_release_struct+0xb8/0xd0 drivers/tty/tty_io.c:1692
 tty_release+0xcb0/0x1640 drivers/tty/tty_io.c:1852
 __fput+0x449/0xa70 fs/file_table.c:468
 task_work_run+0x1d4/0x260 kernel/task_work.c:227
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x6b5/0x2300 kernel/exit.c:961
 do_group_exit+0x21c/0x2d0 kernel/exit.c:1102
 get_signal+0x1286/0x1340 kernel/signal.c:3034
 arch_do_signal_or_restart+0x9a/0x750 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop+0x75/0x130 kernel/entry/common.c:40
 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
 do_syscall_64+0x2bd/0xfa0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Second to last potentially related work creation:
 kasan_save_stack+0x3e/0x60 mm/kasan/common.c:56
 kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:559
 insert_work+0x3d/0x330 kernel/workqueue.c:2184
 __queue_work+0xcd2/0xfb0 kernel/workqueue.c:2339
 queue_work_on+0x181/0x270 kernel/workqueue.c:2390
 serial8250_modem_status+0x1ac/0x2a0 drivers/tty/serial/8250/8250_port.c:1747
 serial8250_handle_irq+0x576/0xbb0 drivers/tty/serial/8250/8250_port.c:1824
 serial8250_default_handle_irq+0xbf/0x200 drivers/tty/serial/8250/8250_port.c:1846
 serial8250_interrupt+0x8d/0x180 drivers/tty/serial/8250/8250_core.c:82
 __handle_irq_event_percpu+0x289/0x980 kernel/irq/handle.c:158
 handle_irq_event_percpu kernel/irq/handle.c:193 [inline]
 handle_irq_event+0x8b/0x1e0 kernel/irq/handle.c:210
 handle_edge_irq+0x23b/0xa10 kernel/irq/chip.c:855
 generic_handle_irq_desc include/linux/irqdesc.h:173 [inline]
 handle_irq arch/x86/kernel/irq.c:254 [inline]
 call_irq_handler arch/x86/kernel/irq.c:-1 [inline]
 __common_interrupt+0x141/0x1f0 arch/x86/kernel/irq.c:325
 common_interrupt+0x5e/0xe0 arch/x86/kernel/irq.c:318
 asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:688

The buggy address belongs to the object at ffff88805b60b000
 which belongs to the cache kmalloc-cg-2k of size 2048
The buggy address is located 1528 bytes inside of
 freed 2048-byte region [ffff88805b60b000, ffff88805b60b800)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff88805b60f000 pfn:0x5b608
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
memcg:ffff88804b098901
flags: 0xfff00000000240(workingset|head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000240 ffff88801a84b3c0 ffffea00009f7c10 ffffea0001dff610
raw: ffff88805b60f000 0000000000080007 00000000f5000000 ffff88804b098901
head: 00fff00000000240 ffff88801a84b3c0 ffffea00009f7c10 ffffea0001dff610
head: ffff88805b60f000 0000000000080007 00000000f5000000 ffff88804b098901
head: 00fff00000000003 ffffea00016d8201 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 16145, tgid 16145 (syz-executor), ts 316122070478, free_ts 302126180398
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1851
 prep_new_page mm/page_alloc.c:1859 [inline]
 get_page_from_freelist+0x21e4/0x22c0 mm/page_alloc.c:3858
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5148
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2416
 alloc_slab_page mm/slub.c:2487 [inline]
 allocate_slab+0x8a/0x330 mm/slub.c:2655
 new_slab mm/slub.c:2709 [inline]
 ___slab_alloc+0xbd1/0x13e0 mm/slub.c:3891
 __slab_alloc mm/slub.c:3981 [inline]
 __slab_alloc_node mm/slub.c:4056 [inline]
 slab_alloc_node mm/slub.c:4217 [inline]
 __do_kmalloc_node mm/slub.c:4364 [inline]
 __kmalloc_noprof+0x2f1/0x4b0 mm/slub.c:4377
 kmalloc_noprof include/linux/slab.h:913 [inline]
 kzalloc_noprof include/linux/slab.h:1043 [inline]
 __register_sysctl_table+0x72/0x1340 fs/proc/proc_sysctl.c:1379
 __devinet_sysctl_register+0x37f/0x470 net/ipv4/devinet.c:2678
 devinet_sysctl_register+0x187/0x200 net/ipv4/devinet.c:2718
 inetdev_init+0x2b4/0x500 net/ipv4/devinet.c:291
 inetdev_event+0x301/0x15b0 net/ipv4/devinet.c:1591
 notifier_call_chain+0x1b3/0x3e0 kernel/notifier.c:85
 call_netdevice_notifiers_extack net/core/dev.c:2267 [inline]
 call_netdevice_notifiers net/core/dev.c:2281 [inline]
 register_netdevice+0x1608/0x1ae0 net/core/dev.c:11244
 geneve_configure+0x645/0xa80 drivers/net/geneve.c:1406
 geneve_newlink+0x188/0x220 drivers/net/geneve.c:1674
page last free pid 15271 tgid 15271 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1395 [inline]
 __free_frozen_pages+0xbc4/0xd30 mm/page_alloc.c:2895
 discard_slab mm/slub.c:2753 [inline]
 __put_partials+0x146/0x170 mm/slub.c:3218
 put_cpu_partial+0x17c/0x250 mm/slub.c:3293
 __slab_free+0x2b9/0x390 mm/slub.c:4550
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x97/0x140 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:349
 kasan_slab_alloc include/linux/kasan.h:250 [inline]
 slab_post_alloc_hook mm/slub.c:4180 [inline]
 slab_alloc_node mm/slub.c:4229 [inline]
 kmem_cache_alloc_noprof+0x1ad/0x390 mm/slub.c:4236
 anon_vma_chain_alloc mm/rmap.c:142 [inline]
 __anon_vma_prepare+0xcb/0x4a0 mm/rmap.c:195
 __vmf_anon_prepare mm/memory.c:3634 [inline]
 vmf_anon_prepare mm/internal.h:432 [inline]
 do_anonymous_page mm/memory.c:5178 [inline]
 do_pte_missing mm/memory.c:4360 [inline]
 handle_pte_fault mm/memory.c:6182 [inline]
 __handle_mm_fault+0x4aff/0x5400 mm/memory.c:6323
 handle_mm_fault+0x40a/0x8e0 mm/memory.c:6492
 do_user_addr_fault+0xa81/0x1390 arch/x86/mm/fault.c:1336
 handle_page_fault arch/x86/mm/fault.c:1476 [inline]
 exc_page_fault+0x82/0x100 arch/x86/mm/fault.c:1532
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618

Memory state around the buggy address:
 ffff88805b60b480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88805b60b500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88805b60b580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                                ^
 ffff88805b60b600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88805b60b680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/08/27 04:08 linux-next 7fa4d8dc380f e12e5ba4 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce KASAN: slab-use-after-free Read in uart_write
* Struck through repros no longer work on HEAD.