KASAN: use-after-free Read in gadgets_drop

Status: premoderation: reported syz repro on 2026/10/12 14:54
Reported-by: syzbot+03847ff704cda7d5a03f@syzkaller.appspotmail.com
First crash: 19d, last: 8d12h
▶ ▼ Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-5-15 KASAN: use-after-free Read in gadgets_drop 19 syz 5 11d 11d 0/2 premoderation: reported syz repro on 2026/10/20 01:23

Sample crash report:
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa23fd9dfac R14: 00007fa23fd9dfa0 R15: 00007fa23fd9dfa0
==================================================================
BUG: KASAN: use-after-free in android_device_destroy drivers/usb/gadget/configfs.c:1820 [inline]
BUG: KASAN: use-after-free in gadgets_drop+0x40/0xd0 drivers/usb/gadget/configfs.c:1902
Read of size 8 at addr ffff888118795550 by task syz.2.17/396

CPU: 1 PID: 396 Comm: syz.2.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/07/2026
Call Trace:
 __dump_stack+0x21/0x24 lib/dump_stack.c:77
 dump_stack_lvl+0x1a7/0x208 lib/dump_stack.c:118
 print_address_description+0x7f/0x2c0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:435 [inline]
 kasan_report+0x100/0x140 mm/kasan/report.c:452
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report_generic.c:309
 android_device_destroy drivers/usb/gadget/configfs.c:1820 [inline]
 gadgets_drop+0x40/0xd0 drivers/usb/gadget/configfs.c:1902
 client_drop_item+0x94/0xc0 fs/configfs/dir.c:985
 configfs_mkdir+0xaca/0xd90 fs/configfs/dir.c:1477
 vfs_mkdir+0x42c/0x600 fs/namei.c:3840
 do_mkdirat+0x14c/0x340 fs/namei.c:3862
 __do_sys_mkdirat fs/namei.c:3873 [inline]
 __se_sys_mkdirat fs/namei.c:3871 [inline]
 __x64_sys_mkdirat+0x7b/0x90 fs/namei.c:3871
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7fa23fb17559
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:00007ffdf63a59e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007fa23fd9dfa0 RCX: 00007fa23fb17559
RDX: 00000000000001ff RSI: 00002000000000c0 RDI: ffffffffffffff9c
RBP: 00007fa23fbaeb20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa23fd9dfac R14: 00007fa23fd9dfa0 R15: 00007fa23fd9dfa0

Allocated by task 396:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track mm/kasan/common.c:45 [inline]
 set_alloc_info mm/kasan/common.c:430 [inline]
 ____kasan_kmalloc mm/kasan/common.c:509 [inline]
 __kasan_kmalloc+0xd4/0x100 mm/kasan/common.c:518
 kasan_kmalloc include/linux/kasan.h:254 [inline]
 kmem_cache_alloc_trace+0x179/0x2e0 mm/slub.c:2979
 kmalloc include/linux/slab.h:555 [inline]
 kzalloc include/linux/slab.h:667 [inline]
 gadgets_make+0x57/0xa70 drivers/usb/gadget/configfs.c:1840
 configfs_mkdir+0x5d2/0xd90 fs/configfs/dir.c:1378
 vfs_mkdir+0x42c/0x600 fs/namei.c:3840
 do_mkdirat+0x14c/0x340 fs/namei.c:3862
 __do_sys_mkdirat fs/namei.c:3873 [inline]
 __se_sys_mkdirat fs/namei.c:3871 [inline]
 __x64_sys_mkdirat+0x7b/0x90 fs/namei.c:3871
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb

Freed by task 396:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track+0x4a/0x70 mm/kasan/common.c:45
 kasan_set_free_info+0x23/0x40 mm/kasan/generic.c:370
 ____kasan_slab_free+0x125/0x160 mm/kasan/common.c:362
 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:370
 kasan_slab_free include/linux/kasan.h:220 [inline]
 slab_free_hook mm/slub.c:1600 [inline]
 slab_free_freelist_hook+0xc5/0x190 mm/slub.c:1626
 slab_free mm/slub.c:3208 [inline]
 kfree+0xc0/0x270 mm/slub.c:4196
 gadget_info_attr_release+0xcb/0xf0 drivers/usb/gadget/configfs.c:429
 config_item_cleanup fs/configfs/item.c:130 [inline]
 config_item_release fs/configfs/item.c:139 [inline]
 kref_put include/linux/kref.h:65 [inline]
 config_item_put+0x158/0x210 fs/configfs/item.c:151
 gadgets_drop+0x23/0xd0 drivers/usb/gadget/configfs.c:1901
 client_drop_item+0x94/0xc0 fs/configfs/dir.c:985
 configfs_mkdir+0xaca/0xd90 fs/configfs/dir.c:1477
 vfs_mkdir+0x42c/0x600 fs/namei.c:3840
 do_mkdirat+0x14c/0x340 fs/namei.c:3862
 __do_sys_mkdirat fs/namei.c:3873 [inline]
 __se_sys_mkdirat fs/namei.c:3871 [inline]
 __x64_sys_mkdirat+0x7b/0x90 fs/namei.c:3871
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb

The buggy address belongs to the object at ffff888118795000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 1360 bytes inside of
 2048-byte region [ffff888118795000, ffff888118795800)
The buggy address belongs to the page:
page:ffffea000461e400 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x118790
head:ffffea000461e400 order:3 compound_mapcount:0 compound_pincount:0
flags: 0x4000000000010200(slab|head)
raw: 4000000000010200 dead000000000100 dead000000000122 ffff888100042d80
raw: 0000000000000000 0000000000080008 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0x1d2a20(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 396, ts 25947540053, free_ts 25877353709
 set_page_owner include/linux/page_owner.h:35 [inline]
 post_alloc_hook mm/page_alloc.c:2456 [inline]
 prep_new_page+0x176/0x190 mm/page_alloc.c:2462
 get_page_from_freelist+0x225f/0x23f0 mm/page_alloc.c:4254
 __alloc_pages_nodemask+0x29a/0x640 mm/page_alloc.c:5384
 alloc_slab_page mm/slub.c:-1 [inline]
 allocate_slab mm/slub.c:1813 [inline]
 new_slab+0x84/0x3f0 mm/slub.c:1874
 new_slab_objects mm/slub.c:2632 [inline]
 ___slab_alloc+0x2f8/0x4c0 mm/slub.c:2796
 __slab_alloc+0x63/0xa0 mm/slub.c:2836
 slab_alloc_node mm/slub.c:2918 [inline]
 slab_alloc mm/slub.c:2960 [inline]
 __kmalloc_track_caller+0x1e4/0x310 mm/slub.c:4541
 __kmalloc_reserve net/core/skbuff.c:144 [inline]
 __alloc_skb+0xdc/0x520 net/core/skbuff.c:212
 alloc_skb include/linux/skbuff.h:1126 [inline]
 nlmsg_new include/net/netlink.h:953 [inline]
 audit_buffer_alloc kernel/audit.c:1806 [inline]
 audit_log_start+0x41b/0x840 kernel/audit.c:1924
 common_lsm_audit+0xd4/0x1850 security/lsm_audit.c:457
 slow_avc_audit+0x1c4/0x240 security/selinux/avc.c:798
 avc_audit security/selinux/include/avc.h:140 [inline]
 avc_has_perm+0x215/0x3d0 security/selinux/avc.c:1201
 may_create+0x2a6/0x7c0 security/selinux/hooks.c:1808
 selinux_inode_mkdir+0x22/0x30 security/selinux/hooks.c:3026
 security_inode_mkdir+0xad/0x110 security/security.c:1191
 vfs_mkdir+0x37e/0x600 fs/namei.c:3833
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:28 [inline]
 free_pages_prepare mm/page_alloc.c:1349 [inline]
 __free_pages_ok+0x80b/0x830 mm/page_alloc.c:1629
 free_the_page mm/page_alloc.c:5445 [inline]
 __free_pages+0xd8/0x390 mm/page_alloc.c:5454
 __free_slab+0xcf/0x190 mm/slub.c:1899
 free_slab mm/slub.c:1914 [inline]
 discard_slab mm/slub.c:1920 [inline]
 unfreeze_partials+0x150/0x180 mm/slub.c:2415
 put_cpu_partial+0xc1/0x180 mm/slub.c:2451
 __slab_free+0x2c9/0x3a0 mm/slub.c:3100
 do_slab_free mm/slub.c:3196 [inline]
 ___cache_free+0x10e/0x130 mm/slub.c:3215
 qlink_free+0x50/0x90 mm/kasan/quarantine.c:157
 qlist_free_all+0x5f/0xb0 mm/kasan/quarantine.c:176
 kasan_quarantine_reduce+0x14a/0x160 mm/kasan/quarantine.c:283
 __kasan_slab_alloc+0x2f/0xe0 mm/kasan/common.c:440
 kasan_slab_alloc include/linux/kasan.h:244 [inline]
 slab_post_alloc_hook+0x5d/0x2f0 mm/slab.h:580
 slab_alloc_node mm/slub.c:2952 [inline]
 slab_alloc mm/slub.c:2960 [inline]
 kmem_cache_alloc_trace+0x155/0x2e0 mm/slub.c:2977
 kmalloc include/linux/slab.h:555 [inline]
 kzalloc include/linux/slab.h:667 [inline]
 ____ip_mc_inc_group+0x1b7/0x8b0 net/ipv4/igmp.c:1456
 __ip_mc_inc_group net/ipv4/igmp.c:1491 [inline]
 ip_mc_inc_group net/ipv4/igmp.c:1497 [inline]
 ip_mc_up+0x112/0x1f0 net/ipv4/igmp.c:1796
 inetdev_event+0xbf2/0x1010 net/ipv4/devinet.c:1587

Memory state around the buggy address:
 ffff888118795400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888118795480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888118795500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                 ^
 ffff888118795580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888118795600: 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
2026/10/23 12:45 android13-5.10-lts d3231d350eb8 d566bfda .config strace log report syz / log [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in gadgets_drop
2026/10/12 15:21 android13-5.10-lts b677692288f7 745a967f .config strace log report syz / log [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in gadgets_drop
2026/10/23 12:02 android13-5.10-lts d3231d350eb8 d566bfda .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in gadgets_drop
2026/10/12 14:53 android13-5.10-lts b677692288f7 745a967f .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in gadgets_drop
* Struck through repros no longer work on HEAD.