KASAN: use-after-free Write in pn_bind

Status: upstream: reported on 2026/07/28 06:20
Reported-by: syzbot+e2a5ffd1302802e8a2cc@syzkaller.appspotmail.com
First crash: 21d, last: 17h11m
Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: slab-use-after-free Write in pn_bind prio:normal usb 22 syz 29 6h16m 17d 0/29 upstream: reported syz repro on 2026/08/01 00:13
linux-6.6 KASAN: slab-use-after-free Write in pn_bind 22 2 19d 19d 0/2 upstream: reported on 2026/07/29 22:52

Sample crash report:
==================================================================
BUG: KASAN: use-after-free in gphonet_set_gadget drivers/usb/gadget/function/f_phonet.c:720 [inline]
BUG: KASAN: use-after-free in pn_bind+0x102/0xb10 drivers/usb/gadget/function/f_phonet.c:510
Write of size 8 at addr ffff888024c446c8 by task syz.6.660/7237

CPU: 0 PID: 7237 Comm: syz.6.660 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:316 [inline]
 print_report+0xa8/0x210 mm/kasan/report.c:420
 kasan_report+0x10b/0x140 mm/kasan/report.c:524
 gphonet_set_gadget drivers/usb/gadget/function/f_phonet.c:720 [inline]
 pn_bind+0x102/0xb10 drivers/usb/gadget/function/f_phonet.c:510
 usb_add_function+0x2d9/0x980 drivers/usb/gadget/composite.c:337
 configfs_composite_bind+0xa02/0xf60 drivers/usb/gadget/configfs.c:1409
 gadget_bind_driver+0x2af/0x760 drivers/usb/gadget/udc/core.c:1651
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x24a/0xb40 drivers/base/dd.c:638
 __driver_probe_device+0x1f5/0x390 drivers/base/dd.c:804
 driver_probe_device+0x4f/0x420 drivers/base/dd.c:834
 __driver_attach+0x43d/0x6c0 drivers/base/dd.c:1220
 bus_for_each_dev+0x182/0x1f0 drivers/base/bus.c:303
 bus_add_driver+0x324/0x5d0 drivers/base/bus.c:620
 driver_register+0x32d/0x430 drivers/base/driver.c:246
 usb_gadget_register_driver_owner+0xf5/0x260 drivers/usb/gadget/udc/core.c:1730
 gadget_dev_desc_UDC_store+0x1c3/0x2e0 drivers/usb/gadget/configfs.c:290
 flush_write_buffer fs/configfs/file.c:207 [inline]
 configfs_write_iter+0x30b/0x400 fs/configfs/file.c:229
 call_write_iter include/linux/fs.h:2265 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x482/0x9a0 fs/read_write.c:584
 ksys_write+0x14d/0x260 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fece059e0d9
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:00007fece14eb028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fece0825fa0 RCX: 00007fece059e0d9
RDX: 000000000000000b RSI: 0000200000000280 RDI: 0000000000000003
RBP: 00007fece0635024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fece0826038 R14: 00007fece0825fa0 R15: 00007ffe83ebc0a8
 </TASK>

Allocated by task 3934:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
 ____kasan_kmalloc mm/kasan/common.c:375 [inline]
 __kasan_kmalloc+0x8e/0xa0 mm/kasan/common.c:384
 kasan_kmalloc include/linux/kasan.h:211 [inline]
 __do_kmalloc_node mm/slab_common.c:936 [inline]
 __kmalloc_node+0xb2/0x240 mm/slab_common.c:943
 kmalloc_node include/linux/slab.h:589 [inline]
 kvmalloc_node+0x6c/0x180 mm/util.c:581
 kvmalloc include/linux/slab.h:716 [inline]
 seq_buf_alloc fs/seq_file.c:38 [inline]
 seq_read_iter+0x1de/0xc50 fs/seq_file.c:210
 call_read_iter include/linux/fs.h:2259 [inline]
 new_sync_read fs/read_write.c:389 [inline]
 vfs_read+0x471/0x960 fs/read_write.c:470
 ksys_read+0x14d/0x260 fs/read_write.c:613
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Freed by task 3934:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
 kasan_save_free_info+0x27/0x40 mm/kasan/generic.c:516
 ____kasan_slab_free+0x126/0x1f0 mm/kasan/common.c:237
 kasan_slab_free include/linux/kasan.h:177 [inline]
 slab_free_hook mm/slub.c:1729 [inline]
 slab_free_freelist_hook+0x133/0x1b0 mm/slub.c:1755
 slab_free mm/slub.c:3687 [inline]
 __kmem_cache_free+0xb6/0x200 mm/slub.c:3700
 seq_release+0x53/0x70 fs/seq_file.c:355
 kernfs_fop_release+0x135/0x190 fs/kernfs/file.c:826
 __fput+0x20a/0x8b0 fs/file_table.c:320
 task_work_run+0x1d0/0x260 kernel/task_work.c:203
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:177
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

The buggy address belongs to the object at ffff888024c44000
 which belongs to the cache kmalloc-cg-4k of size 4096
The buggy address is located 1736 bytes inside of
 4096-byte region [ffff888024c44000, ffff888024c45000)

The buggy address belongs to the physical page:
page:ffffea0000931000 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x24c40
head:ffffea0000931000 order:3 compound_mapcount:0 compound_pincount:0
memcg:ffff888077f19dc1
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 dead000000000100 dead000000000122 ffff88801744c280
raw: 0000000000000000 0000000000040004 00000001ffffffff ffff888077f19dc1
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 6287, tgid 6287 (syz.0.471), ts 179138245978, free_ts 178986734303
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x173/0x1a0 mm/page_alloc.c:2560
 prep_new_page mm/page_alloc.c:2567 [inline]
 get_page_from_freelist+0x206b/0x2180 mm/page_alloc.c:4358
 __alloc_pages+0x1ec/0x4f0 mm/page_alloc.c:5658
 alloc_slab_page+0x5d/0x180 mm/slub.c:1799
 allocate_slab mm/slub.c:1944 [inline]
 new_slab+0x87/0x2d0 mm/slub.c:1997
 ___slab_alloc+0xbc5/0x1240 mm/slub.c:3154
 __slab_alloc mm/slub.c:3240 [inline]
 slab_alloc_node mm/slub.c:3325 [inline]
 __kmem_cache_alloc_node+0x126/0x270 mm/slub.c:3398
 kmalloc_trace+0x26/0xe0 mm/slab_common.c:1026
 kmalloc include/linux/slab.h:563 [inline]
 kzalloc include/linux/slab.h:699 [inline]
 kvm_uevent_notify_change+0xc6/0x3a0 virt/kvm/kvm_main.c:5707
 kvm_destroy_vm virt/kvm/kvm_main.c:1304 [inline]
 kvm_put_kvm+0x96/0x1a10 virt/kvm/kvm_main.c:1370
 kvm_vm_release+0x42/0x50 virt/kvm/kvm_main.c:1393
 __fput+0x20a/0x8b0 fs/file_table.c:320
 task_work_run+0x1d0/0x260 kernel/task_work.c:203
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:177
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1487 [inline]
 free_pcp_prepare mm/page_alloc.c:1537 [inline]
 free_unref_page_prepare+0x8e5/0x9e0 mm/page_alloc.c:3414
 free_unref_page+0x2e/0x3f0 mm/page_alloc.c:3509
 free_slab mm/slub.c:2036 [inline]
 discard_slab mm/slub.c:2042 [inline]
 __unfreeze_partials+0x188/0x1e0 mm/slub.c:2591
 put_cpu_partial+0x17c/0x250 mm/slub.c:2667
 qlink_free mm/kasan/quarantine.c:168 [inline]
 qlist_free_all+0x76/0xe0 mm/kasan/quarantine.c:187
 kasan_quarantine_reduce+0x144/0x160 mm/kasan/quarantine.c:294
 __kasan_slab_alloc+0x1e/0x80 mm/kasan/common.c:306
 kasan_slab_alloc include/linux/kasan.h:201 [inline]
 slab_post_alloc_hook+0x4b/0x490 mm/slab.h:737
 slab_alloc_node mm/slub.c:3359 [inline]
 slab_alloc mm/slub.c:3367 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3374 [inline]
 kmem_cache_alloc_lru+0x182/0x2e0 mm/slub.c:3390
 __d_alloc+0x2e/0x6e0 fs/dcache.c:1774
 d_alloc_anon fs/dcache.c:1875 [inline]
 d_alloc_cursor+0x40/0xd0 fs/dcache.c:1881
 dcache_dir_open+0x37/0x70 fs/libfs.c:83
 do_dentry_open+0x7dd/0x10b0 fs/open.c:882
 do_open fs/namei.c:3634 [inline]
 path_openat+0x2674/0x2f10 fs/namei.c:3791
 do_filp_open+0x1ee/0x420 fs/namei.c:3818
 do_sys_openat2+0x14b/0x4f0 fs/open.c:1320

Memory state around the buggy address:
 ffff888024c44580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888024c44600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888024c44680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                              ^
 ffff888024c44700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888024c44780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/18 05:16 linux-6.1.y e4f7d8be268e 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Write in pn_bind
2026/08/04 19:03 linux-6.1.y fb28aa725e05 d4abbeac .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Write in pn_bind
2026/08/02 18:04 linux-6.1.y fb28aa725e05 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Write in pn_bind
2026/07/29 21:42 linux-6.1.y 1016ca6176ee 6ef5c1e2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Write in pn_bind
2026/07/28 06:19 linux-6.1.y dc5c83b7f5f8 45ae1df4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Write in pn_bind
* Struck through repros no longer work on HEAD.