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

Status: moderation: reported on 2026/08/24 05:03
Subsystems: perf trace
Labels: prio:normal
[Documentation on labels]
Reported-by: syzbot+1340ad4350ad43394c10@syzkaller.appspotmail.com
First crash: 5d23h, last: 5d23h
▶ ▼ ✨ AI Jobs (2)
ID Workflow Result Correct Bug Created Started Finished Revision
0109efb0 moderation Actionable: ❌ ❓ KASAN: slab-use-after-free Read in uprobe_mmap (2) 2026/08/25 00:28 2026/08/25 00:28 2026/08/25 00:52 23caa175
a47efa9d assessment-security DenialOfService: ✅ Exploitable: ✅ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ KASAN: slab-use-after-free Read in uprobe_mmap (2) 2026/08/22 00:00 2026/08/22 00:00 2026/08/22 01:13 1e72964b
▶ ▼ Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: slab-use-after-free Read in uprobe_mmap perf trace 19 67 715d 762d 0/29 auto-obsoleted due to no activity on 2024/11/18 21:02
upstream KASAN: use-after-free Read in uprobe_mmap kernel 19 228 2024d 2031d 0/29 auto-closed as invalid on 2021/03/20 18:26

Sample crash report:
==================================================================
BUG: KASAN: slab-use-after-free in consumer_filter kernel/events/uprobes.c:1133 [inline]
BUG: KASAN: slab-use-after-free in filter_chain kernel/events/uprobes.c:1143 [inline]
BUG: KASAN: slab-use-after-free in uprobe_mmap+0xee9/0x13c0 kernel/events/uprobes.c:1628
Read of size 8 at addr ffff88803308a028 by task syz.4.5122/24257

CPU: 0 UID: 0 PID: 24257 Comm: syz.4.5122 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description+0x55/0x1e0 mm/kasan/report.c:378
 print_report+0x58/0x70 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 consumer_filter kernel/events/uprobes.c:1133 [inline]
 filter_chain kernel/events/uprobes.c:1143 [inline]
 uprobe_mmap+0xee9/0x13c0 kernel/events/uprobes.c:1628
 __mmap_complete+0x421/0x4b0 mm/vma.c:2628
 __mmap_region mm/vma.c:2783 [inline]
 mmap_region+0x119f/0x2310 mm/vma.c:2860
 do_mmap+0xc3b/0x10c0 mm/mmap.c:560
 vm_mmap_pgoff+0x272/0x4e0 mm/util.c:581
 ksys_mmap_pgoff+0x4dc/0x760 mm/mmap.c:606
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f31e079e0d9
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:00007f31e15ea028 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007f31e0a25fa0 RCX: 00007f31e079e0d9
RDX: 0000000000000005 RSI: 0000000000001000 RDI: 0000200000800000
RBP: 00007f31e0835024 R08: 0000000000000006 R09: 0000000000000000
R10: 0000000000000012 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f31e0a26038 R14: 00007f31e0a25fa0 R15: 00007fff326afa98
 </TASK>

Allocated by task 5849:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __do_kmalloc_node mm/slub.c:5334 [inline]
 __kmalloc_noprof+0x379/0x720 mm/slub.c:5359
 _kmalloc_noprof include/linux/slab.h:992 [inline]
 usb_alloc_urb+0x46/0x150 drivers/usb/core/urb.c:75
 usb_internal_control_msg drivers/usb/core/message.c:110 [inline]
 usb_control_msg+0x118/0x3e0 drivers/usb/core/message.c:167
 set_port_feature drivers/usb/core/hub.c:466 [inline]
 hub_port_reset+0x3ca/0x1810 drivers/usb/core/hub.c:3091
 hub_port_init+0x2a1/0x28c0 drivers/usb/core/hub.c:4947
 hub_port_connect drivers/usb/core/hub.c:5504 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5715 [inline]
 port_event drivers/usb/core/hub.c:5879 [inline]
 hub_event+0x24e8/0x4d30 drivers/usb/core/hub.c:5961
 process_one_work kernel/workqueue.c:3322 [inline]
 process_scheduled_works+0xa88/0x14c0 kernel/workqueue.c:3405
 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3486
 kthread+0x38b/0x480 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Freed by task 5849:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2677 [inline]
 slab_free mm/slub.c:6377 [inline]
 kfree+0x1c5/0x640 mm/slub.c:6692
 usb_start_wait_urb+0x4ba/0x5b0 drivers/usb/core/message.c:95
 usb_internal_control_msg drivers/usb/core/message.c:117 [inline]
 usb_control_msg+0x234/0x3e0 drivers/usb/core/message.c:167
 set_port_feature drivers/usb/core/hub.c:466 [inline]
 hub_port_reset+0x3ca/0x1810 drivers/usb/core/hub.c:3091
 hub_port_init+0x2a1/0x28c0 drivers/usb/core/hub.c:4947
 hub_port_connect drivers/usb/core/hub.c:5504 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5715 [inline]
 port_event drivers/usb/core/hub.c:5879 [inline]
 hub_event+0x24e8/0x4d30 drivers/usb/core/hub.c:5961
 process_one_work kernel/workqueue.c:3322 [inline]
 process_scheduled_works+0xa88/0x14c0 kernel/workqueue.c:3405
 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3486
 kthread+0x38b/0x480 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

The buggy address belongs to the object at ffff88803308a000
 which belongs to the cache kmalloc-192 of size 192
The buggy address is located 40 bytes inside of
 freed 192-byte region [ffff88803308a000, ffff88803308a0c0)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x3308a
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000000 ffff88813fe3f3c0 dead000000000100 dead000000000122
raw: 0000000000000000 0000000800100010 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 19914146595, free_ts 0
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1f9/0x250 mm/page_alloc.c:1859
 prep_new_page mm/page_alloc.c:1867 [inline]
 get_page_from_freelist+0x21fe/0x2270 mm/page_alloc.c:3946
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5304
 alloc_slab_page mm/slub.c:3266 [inline]
 allocate_slab+0x79/0x5e0 mm/slub.c:3380
 new_slab mm/slub.c:3426 [inline]
 refill_objects+0x2d5/0x350 mm/slub.c:7310
 refill_sheaf mm/slub.c:2804 [inline]
 __pcs_replace_empty_main+0x2c3/0x6b0 mm/slub.c:4675
 alloc_from_pcs mm/slub.c:4773 [inline]
 slab_alloc_node mm/slub.c:4905 [inline]
 __kmalloc_cache_noprof+0x3ab/0x660 mm/slub.c:5485
 _kmalloc_noprof include/linux/slab.h:988 [inline]
 _kzalloc_noprof include/linux/slab.h:1309 [inline]
 call_usermodehelper_setup+0x8e/0x270 kernel/umh.c:360
 kobject_uevent_env+0x662/0x9e0 lib/kobject_uevent.c:631
 kernel_add_sysfs_param+0xb1/0xe0 kernel/params.c:801
 param_sysfs_builtin+0x199/0x250 kernel/params.c:836
 param_sysfs_builtin_init+0x23/0x30 kernel/params.c:972
 do_one_initcall+0x250/0x870 init/main.c:1353
 do_initcall_level+0x10a/0x1a0 init/main.c:1415
 do_initcalls+0x59/0xa0 init/main.c:1431
 kernel_init_freeable+0x29d/0x3e0 init/main.c:1666
page_owner free stack trace missing

Memory state around the buggy address:
 ffff888033089f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888033089f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88803308a000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                  ^
 ffff88803308a080: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff88803308a100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/20 05:03 upstream 98f21c54f995 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root KASAN: slab-use-after-free Read in uprobe_mmap
2026/08/20 05:01 upstream 98f21c54f995 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root KASAN: slab-use-after-free Read in uprobe_mmap
* Struck through repros no longer work on HEAD.