KASAN: slab-out-of-bounds Read in dummy_free_request

Status: upstream: reported on 2026/07/24 21:58
Reported-by: syzbot+b64626956b36064cb03c@syzkaller.appspotmail.com
First crash: 57d, last: 39d
▶ ▼ Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 KASAN: slab-out-of-bounds Read in dummy_free_request 17 19 19d 57d 0/3 upstream: reported on 2026/07/24 22:09
upstream KASAN: slab-out-of-bounds Read in dummy_free_request prio:normal usb 17 162 23d 53d 0/29 upstream: reported on 2026/07/29 00:19
linux-6.6 KASAN: slab-out-of-bounds Read in dummy_free_request 17 2 48d 50d 0/2 upstream: reported on 2026/07/31 17:51

Sample crash report:
configfs-gadget gadget: uvc: uvc_function_bind()
configfs-gadget gadget: uvc: Unable to allocate streaming EP
==================================================================
BUG: KASAN: slab-out-of-bounds in list_empty include/linux/list.h:290 [inline]
BUG: KASAN: slab-out-of-bounds in dummy_free_request+0x3b/0x70 drivers/usb/gadget/udc/dummy_hcd.c:687
Read of size 8 at addr ffff88801eb466f0 by task syz.0.754/7494

CPU: 0 PID: 7494 Comm: syz.0.754 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 print_address_description+0x60/0x2d0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:434 [inline]
 kasan_report+0xdf/0x130 mm/kasan/report.c:451
 list_empty include/linux/list.h:290 [inline]
 dummy_free_request+0x3b/0x70 drivers/usb/gadget/udc/dummy_hcd.c:687
 uvc_function_bind+0xe24/0x12d0 drivers/usb/gadget/function/f_uvc.c:785
 usb_add_function+0x2d9/0x980 drivers/usb/gadget/composite.c:324
 configfs_composite_bind+0xa02/0xf60 drivers/usb/gadget/configfs.c:1417
 udc_bind_to_driver+0x203/0x5f0 drivers/usb/gadget/udc/core.c:1574
 usb_gadget_probe_driver+0x1fb/0x380 drivers/usb/gadget/udc/core.c:1637
 gadget_dev_desc_UDC_store+0x1ba/0x2e0 drivers/usb/gadget/configfs.c:289
 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:2173 [inline]
 new_sync_write fs/read_write.c:507 [inline]
 vfs_write+0x748/0xd70 fs/read_write.c:594
 ksys_write+0x153/0x260 fs/read_write.c:647
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f714ac300d9
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:00007f7148e88028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f714aeb7fa0 RCX: 00007f714ac300d9
RDX: 000000000000000b RSI: 0000200000000380 RDI: 0000000000000005
RBP: 00007f714acc7024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f714aeb8038 R14: 00007f714aeb7fa0 R15: 00007fff1a3e8b78
 </TASK>

Allocated by task 4188:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track mm/kasan/common.c:46 [inline]
 set_alloc_info mm/kasan/common.c:434 [inline]
 ____kasan_kmalloc mm/kasan/common.c:513 [inline]
 __kasan_kmalloc+0xaf/0xe0 mm/kasan/common.c:522
 kmalloc_array_node include/linux/slab.h:700 [inline]
 kcalloc_node include/linux/slab.h:705 [inline]
 memcg_alloc_page_obj_cgroups+0x7d/0x120 mm/memcontrol.c:2839
 memcg_slab_post_alloc_hook mm/slab.h:313 [inline]
 slab_post_alloc_hook+0xba/0x380 mm/slab.h:526
 slab_alloc_node mm/slub.c:3225 [inline]
 slab_alloc mm/slub.c:3233 [inline]
 kmem_cache_alloc+0x15d/0x280 mm/slub.c:3238
 vm_area_dup kernel/fork.c:359 [inline]
 dup_mmap kernel/fork.c:558 [inline]
 dup_mm kernel/fork.c:1467 [inline]
 copy_mm+0x8b6/0x13d0 kernel/fork.c:1519
 copy_process+0x17fb/0x3ec0 kernel/fork.c:2291
 kernel_clone+0x23f/0x990 kernel/fork.c:2681
 __do_sys_clone kernel/fork.c:2798 [inline]
 __se_sys_clone kernel/fork.c:2782 [inline]
 __x64_sys_clone+0x19a/0x210 kernel/fork.c:2782
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0

The buggy address belongs to the object at ffff88801eb46600
 which belongs to the cache kmalloc-128 of size 128
The buggy address is located 112 bytes to the right of
 128-byte region [ffff88801eb46600, ffff88801eb46680)
The buggy address belongs to the page:
page:ffffea00007ad180 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88801eb46100 pfn:0x1eb46
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000200 ffffea00017da588 ffffea0000a97008 ffff888016c418c0
raw: ffff88801eb46100 000000000010000c 00000001ffffffff 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 0x12cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY), pid 3564, ts 31540030762, free_ts 31522783916
 prep_new_page mm/page_alloc.c:2426 [inline]
 get_page_from_freelist+0x24f6/0x2670 mm/page_alloc.c:4192
 __alloc_pages+0x1ee/0x480 mm/page_alloc.c:5501
 alloc_slab_page mm/slub.c:1780 [inline]
 allocate_slab mm/slub.c:1917 [inline]
 new_slab+0xc0/0x4b0 mm/slub.c:1980
 ___slab_alloc+0x807/0xdd0 mm/slub.c:3013
 __slab_alloc mm/slub.c:3100 [inline]
 slab_alloc_node mm/slub.c:3191 [inline]
 slab_alloc mm/slub.c:3233 [inline]
 kmem_cache_alloc_trace+0xf9/0x290 mm/slub.c:3250
 kmalloc include/linux/slab.h:607 [inline]
 kernfs_get_open_node fs/kernfs/file.c:552 [inline]
 kernfs_fop_open+0x887/0xba0 fs/kernfs/file.c:698
 do_dentry_open+0x7f7/0xf90 fs/open.c:826
 do_open fs/namei.c:3616 [inline]
 path_openat+0x2718/0x2fb0 fs/namei.c:3750
 do_filp_open+0x1df/0x400 fs/namei.c:3777
 do_sys_openat2+0x14b/0x500 fs/open.c:1255
 do_sys_open fs/open.c:1271 [inline]
 __do_sys_openat fs/open.c:1287 [inline]
 __se_sys_openat fs/open.c:1282 [inline]
 __x64_sys_openat+0x135/0x160 fs/open.c:1282
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1340 [inline]
 free_pcp_prepare mm/page_alloc.c:1391 [inline]
 free_unref_page_prepare+0x637/0x6c0 mm/page_alloc.c:3317
 free_unref_page+0x8f/0x2a0 mm/page_alloc.c:3396
 qlist_free_all+0x35/0x90 mm/kasan/quarantine.c:176
 kasan_quarantine_reduce+0x150/0x160 mm/kasan/quarantine.c:283
 __kasan_slab_alloc+0x2f/0xc0 mm/kasan/common.c:444
 kasan_slab_alloc include/linux/kasan.h:254 [inline]
 slab_post_alloc_hook+0x4c/0x380 mm/slab.h:519
 slab_alloc_node mm/slub.c:3225 [inline]
 __kmalloc_node+0x1ae/0x3a0 mm/slub.c:4456
 kmalloc_node include/linux/slab.h:630 [inline]
 kvmalloc_node+0x84/0x130 mm/util.c:619
 kvmalloc include/linux/mm.h:816 [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:2167 [inline]
 new_sync_read fs/read_write.c:404 [inline]
 vfs_read+0x75e/0xd50 fs/read_write.c:485
 ksys_read+0x153/0x260 fs/read_write.c:623
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0

Memory state around the buggy address:
 ffff88801eb46580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88801eb46600: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 fc
>ffff88801eb46680: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                                                             ^
 ffff88801eb46700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88801eb46780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================

Crashes (7):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/11 17:36 linux-5.15.y aabd761612db 71790083 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan KASAN: slab-out-of-bounds Read in dummy_free_request
2026/08/11 17:36 linux-5.15.y aabd761612db 71790083 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan KASAN: slab-out-of-bounds Read in dummy_free_request
2026/08/07 17:55 linux-5.15.y aabd761612db e4ef95d6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan KASAN: slab-out-of-bounds Read in dummy_free_request
2026/07/31 16:31 linux-5.15.y 6e2fd6534337 7664cf44 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan KASAN: slab-out-of-bounds Read in dummy_free_request
2026/07/24 22:02 linux-5.15.y 674f684f7c61 dd737a83 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan KASAN: slab-out-of-bounds Read in dummy_free_request
2026/07/24 21:58 linux-5.15.y 674f684f7c61 dd737a83 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan KASAN: slab-out-of-bounds Read in dummy_free_request
2026/07/24 21:57 linux-5.15.y 674f684f7c61 dd737a83 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan KASAN: slab-out-of-bounds Read in dummy_free_request
* Struck through repros no longer work on HEAD.