syzbot

 sign-in | mailing list | source | docs
🐞 Open [1491]
≡ Subsystems
🐞 Fixed [6693]
🐞 Invalid [17164]
⬇ Missing Backports [216]
≡ Crashes
Kernel Health Bugs/Month Bug Lifetimes Fuzzing
Total Repo Heatmap Subsystems Heatmap
💬 Send us feedback

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

Status: moderation: reported on 2025/06/07 00:10
Subsystems: bluetooth
[Documentation on labels]
Reported-by: syzbot+8a25818899ba4e66ede2@syzkaller.appspotmail.com
First crash: 150d, last: 50d
▶ ▼ Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-54 KASAN: use-after-free Read in skb_dequeue 19 syz 1 1537d 1537d 0/2 auto-obsoleted due to no activity on 2023/04/23 02:47
upstream general protection fault in skb_dequeue (3) wireless 2 C done 6 993d 1003d 22/29 fixed on 2023/06/08 14:41
upstream general protection fault in skb_dequeue (2) bluetooth 19 C inconclusive done 9 1482d 1566d 0/29 auto-closed as invalid on 2022/10/03 17:36
linux-4.19 KASAN: use-after-free Read in skb_dequeue (2) 19 C done 2 1507d 1537d 1/1 fixed on 2021/10/15 14:38

Sample crash report:
==================================================================
BUG: KASAN: slab-use-after-free in rt_spin_lock+0x88/0x2c0 kernel/locking/spinlock_rt.c:56
Read of size 1 at addr ffff888031e94210 by task kworker/1:0/31

CPU: 1 UID: 0 PID: 31 Comm: kworker/1:0 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Workqueue: events btusb_rx_work
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
 __kasan_check_byte+0x2a/0x40 mm/kasan/common.c:568
 kasan_check_byte include/linux/kasan.h:399 [inline]
 lock_acquire+0x8d/0x360 kernel/locking/lockdep.c:5842
 rt_spin_lock+0x88/0x2c0 kernel/locking/spinlock_rt.c:56
 spin_lock include/linux/spinlock_rt.h:44 [inline]
 skb_dequeue+0x2c/0x140 net/core/skbuff.c:3895
 btusb_rx_work+0x27/0xd0 drivers/bluetooth/btusb.c:2374
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3319
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400
 kthread+0x70e/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Allocated by task 31:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
 poison_kmalloc_redzone mm/kasan/common.c:388 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:405
 kasan_kmalloc include/linux/kasan.h:260 [inline]
 __do_kmalloc_node mm/slub.c:4365 [inline]
 __kmalloc_node_track_caller_noprof+0x1f3/0x450 mm/slub.c:4384
 alloc_dr drivers/base/devres.c:119 [inline]
 devm_kmalloc+0x7f/0x300 drivers/base/devres.c:864
 devm_kzalloc include/linux/device/devres.h:53 [inline]
 btusb_probe+0x373/0x3560 drivers/bluetooth/btusb.c:3961
 usb_probe_interface+0x665/0xc30 drivers/usb/core/driver.c:396
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x26a/0x9e0 drivers/base/dd.c:659
 __driver_probe_device+0x18c/0x2f0 drivers/base/dd.c:801
 driver_probe_device+0x4f/0x430 drivers/base/dd.c:831
 __device_attach_driver+0x2ce/0x530 drivers/base/dd.c:959
 bus_for_each_drv+0x254/0x2e0 drivers/base/bus.c:462
 __device_attach+0x2bb/0x400 drivers/base/dd.c:1031
 bus_probe_device+0x188/0x260 drivers/base/bus.c:537
 device_add+0x7b6/0xb50 drivers/base/core.c:3689
 usb_set_configuration+0x1a87/0x20e0 drivers/usb/core/message.c:2210
 usb_generic_driver_probe+0x8d/0x150 drivers/usb/core/generic.c:250
 usb_probe_device+0x1c4/0x390 drivers/usb/core/driver.c:291
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x26a/0x9e0 drivers/base/dd.c:659
 __driver_probe_device+0x18c/0x2f0 drivers/base/dd.c:801
 driver_probe_device+0x4f/0x430 drivers/base/dd.c:831
 __device_attach_driver+0x2ce/0x530 drivers/base/dd.c:959
 bus_for_each_drv+0x254/0x2e0 drivers/base/bus.c:462
 __device_attach+0x2bb/0x400 drivers/base/dd.c:1031
 bus_probe_device+0x188/0x260 drivers/base/bus.c:537
 device_add+0x7b6/0xb50 drivers/base/core.c:3689
 usb_new_device+0xa29/0x16e0 drivers/usb/core/hub.c:2694
 hub_port_connect drivers/usb/core/hub.c:5566 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5706 [inline]
 port_event drivers/usb/core/hub.c:5870 [inline]
 hub_event+0x2958/0x4a20 drivers/usb/core/hub.c:5952
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3319
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400
 kthread+0x70e/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Freed by task 9:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:576
 poison_slab_object mm/kasan/common.c:243 [inline]
 __kasan_slab_free+0x5b/0x80 mm/kasan/common.c:275
 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+0x195/0x550 mm/slub.c:4879
 release_nodes drivers/base/devres.c:506 [inline]
 devres_release_all+0x1a0/0x220 drivers/base/devres.c:535
 device_unbind_cleanup drivers/base/dd.c:550 [inline]
 __device_release_driver drivers/base/dd.c:1279 [inline]
 device_release_driver_internal+0x55b/0x800 drivers/base/dd.c:1297
 bus_remove_device+0x355/0x420 drivers/base/bus.c:579
 device_del+0x515/0x8e0 drivers/base/core.c:3878
 usb_disable_device+0x3e9/0x8a0 drivers/usb/core/message.c:1418
 usb_disconnect+0x316/0x940 drivers/usb/core/hub.c:2344
 hub_port_connect drivers/usb/core/hub.c:5406 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5706 [inline]
 port_event drivers/usb/core/hub.c:5870 [inline]
 hub_event+0x1cf5/0x4a20 drivers/usb/core/hub.c:5952
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3319
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400
 kthread+0x70e/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x3f9/0x770 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:47
 kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:548
 insert_work+0x3d/0x330 kernel/workqueue.c:2184
 __queue_work+0xd63/0x1010 kernel/workqueue.c:2339
 queue_delayed_work_on+0x18b/0x280 kernel/workqueue.c:2559
 queue_delayed_work include/linux/workqueue.h:684 [inline]
 schedule_delayed_work include/linux/workqueue.h:824 [inline]
 btusb_recv_event drivers/bluetooth/btusb.c:1145 [inline]
 btusb_recv_intr+0x3c7/0x640 drivers/bluetooth/btusb.c:1196
 btusb_intr_complete+0x164/0x490 drivers/bluetooth/btusb.c:1381
 __usb_hcd_giveback_urb+0x3b4/0x5e0 drivers/usb/core/hcd.c:1661
 dummy_timer+0x89c/0x45a0 drivers/usb/gadget/udc/dummy_hcd.c:1995
 __run_hrtimer kernel/time/hrtimer.c:1761 [inline]
 __hrtimer_run_queues+0x552/0xd40 kernel/time/hrtimer.c:1825
 hrtimer_run_softirq+0x1a3/0x2e0 kernel/time/hrtimer.c:1842
 handle_softirqs+0x22f/0x710 kernel/softirq.c:579
 __do_softirq kernel/softirq.c:613 [inline]
 run_ktimerd+0xcf/0x190 kernel/softirq.c:1043
 smpboot_thread_fn+0x53f/0xa60 kernel/smpboot.c:160
 kthread+0x70e/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

The buggy address belongs to the object at ffff888031e94000
 which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 528 bytes inside of
 freed 4096-byte region [ffff888031e94000, ffff888031e95000)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff888031e96000 pfn:0x31e90
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x80000000000240(workingset|head|node=0|zone=1)
page_type: f5(slab)
raw: 0080000000000240 ffff888019842140 ffffea0000c5e610 ffffea0000c57210
raw: ffff888031e96000 0000000000040003 00000000f5000000 0000000000000000
head: 0080000000000240 ffff888019842140 ffffea0000c5e610 ffffea0000c57210
head: ffff888031e96000 0000000000040003 00000000f5000000 0000000000000000
head: 0080000000000003 ffffea0000c7a401 00000000ffffffff 00000000ffffffff
head: 0000000000000000 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 0xd2040(__GFP_IO|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5217, tgid 5217 (udevd), ts 52387489047, free_ts 52380631517
 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+0x2119/0x21b0 mm/page_alloc.c:3858
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5148
 alloc_pages_mpol+0xd1/0x380 mm/mempolicy.c:2416
 alloc_slab_page mm/slub.c:2487 [inline]
 allocate_slab+0x8a/0x370 mm/slub.c:2655
 new_slab mm/slub.c:2709 [inline]
 ___slab_alloc+0x8d1/0xdd0 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+0x145/0x430 mm/slub.c:4377
 kmalloc_noprof include/linux/slab.h:909 [inline]
 tomoyo_realpath_from_path+0xe3/0x5d0 security/tomoyo/realpath.c:251
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_path_perm+0x213/0x4b0 security/tomoyo/file.c:822
 security_inode_getattr+0x12f/0x330 security/security.c:2377
 vfs_getattr fs/stat.c:259 [inline]
 vfs_statx_path fs/stat.c:299 [inline]
 vfs_statx+0x18e/0x550 fs/stat.c:356
 vfs_fstatat+0x118/0x170 fs/stat.c:375
 __do_sys_newfstatat fs/stat.c:542 [inline]
 __se_sys_newfstatat fs/stat.c:536 [inline]
 __x64_sys_newfstatat+0x116/0x190 fs/stat.c:536
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 5215 tgid 5215 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1395 [inline]
 __free_frozen_pages+0xb59/0xce0 mm/page_alloc.c:2895
 discard_slab mm/slub.c:2753 [inline]
 __put_partials+0x159/0x1a0 mm/slub.c:3218
 __slab_free+0x2b3/0x390 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:340
 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+0x143/0x310 mm/slub.c:4236
 getname_flags+0xb8/0x540 fs/namei.c:146
 do_readlinkat+0xbc/0x500 fs/stat.c:575
 __do_sys_readlink fs/stat.c:613 [inline]
 __se_sys_readlink fs/stat.c:610 [inline]
 __x64_sys_readlink+0x7f/0x90 fs/stat.c:610
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff888031e94100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888031e94180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888031e94200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                         ^
 ffff888031e94280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888031e94300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/09/03 07:41 upstream e6b9dce0aeeb 96a211bc .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root KASAN: slab-use-after-free Read in skb_dequeue
2025/06/03 00:01 upstream d00a83477e7a a30356b7 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream KASAN: slab-use-after-free Read in skb_dequeue
2025/08/26 23:35 upstream fab1beda7597 e12e5ba4 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 KASAN: slab-use-after-free Read in skb_dequeue
2025/09/11 14:33 linux-next 5f540c4aade9 fdeaa69b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce KASAN: slab-use-after-free Read in skb_dequeue
* Struck through repros no longer work on HEAD.