KASAN: slab-out-of-bounds Write in copy_to_urb

Status: upstream: reported C repro on 2025/11/24 08:39
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+cb6f25516cd712ca5054@syzkaller.appspotmail.com
First crash: 262d, last: 178d
Fix bisection the fix commit could be any of (bisect log):
  082b6b511432 mmc: sdhci-of-dwcmshc: Change DLL_STRBIN_TAPNUM_DEFAULT to 0x4
  ece3b981bb66 ALSA: usb-audio: Fix potential overflow of PCM transfer buffer
   
▶ ▼ Bug presence (2)
Date Name Commit Repro Result
2026/01/02 linux-6.6.y (ToT) 5fa4793a2d2d C [report] possible deadlock in snd_usb_endpoint_close
2026/01/02 upstream (ToT) b69053dd3ffb C Didn't crash
▶ ▼ Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 KASAN: slab-out-of-bounds Write in copy_to_urb origin:lts-only 21 syz, C done 7 257d 261d 3/3 fixed on 2026/01/11 15:32
linux-6.1 KASAN: slab-out-of-bounds Write in copy_to_urb (2) origin:lts-only 21 syz, C inconclusive 7 178d 194d 0/3 upstream: reported C repro on 2026/01/31 10:36
upstream KASAN: slab-out-of-bounds Write in copy_to_urb (2) usb sound 21 syz, C 5 214d 212d 29/29 fixed on 2026/05/06 16:40
upstream KASAN: slab-out-of-bounds Write in copy_to_urb usb sound 21 syz, C 33 221d 281d 29/29 fixed on 2026/01/07 12:29
▶ ▼ Fix bisection attempts (6)
Created Duration User Patch Repo Result
2026/06/21 03:34 1h53m fix candidate upstream OK (0) job log
2026/04/25 14:48 14m fix candidate upstream error job log
2026/03/25 05:21 1m fix candidate upstream error job log
2026/02/22 07:44 1m fix candidate upstream error job log
2026/01/23 06:35 1m fix candidate upstream error job log
2025/12/27 14:18 4h41m bisect fix linux-6.6.y OK (2) job log

Sample crash report:
==================================================================
BUG: KASAN: slab-out-of-bounds in copy_to_urb+0x255/0x440 sound/usb/pcm.c:1437
Write of size 264 at addr ffff88801cf65800 by task syz.0.17/5941

CPU: 0 PID: 5941 Comm: syz.0.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:364 [inline]
 print_report+0xac/0x220 mm/kasan/report.c:468
 kasan_report+0x117/0x150 mm/kasan/report.c:581
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x288/0x290 mm/kasan/generic.c:187
 __asan_memcpy+0x40/0x70 mm/kasan/shadow.c:106
 copy_to_urb+0x255/0x440 sound/usb/pcm.c:1437
 prepare_playback_urb+0x932/0x1360 sound/usb/pcm.c:1565
 prepare_outbound_urb+0x372/0xc40 sound/usb/endpoint.c:336
 snd_usb_endpoint_start+0x4d9/0x1440 sound/usb/endpoint.c:1618
 start_endpoints+0xa1/0x270 sound/usb/pcm.c:273
 snd_usb_substream_playback_trigger+0x3e0/0x7a0 sound/usb/pcm.c:1669
 snd_pcm_do_start+0xb1/0x170 sound/core/pcm_native.c:1443
 snd_pcm_action_single sound/core/pcm_native.c:1293 [inline]
 snd_pcm_action+0xda/0x230 sound/core/pcm_native.c:1376
 __snd_pcm_lib_xfer+0x16fa/0x1c40 sound/core/pcm_lib.c:2341
 snd_pcm_oss_write3+0x1bc/0x320 sound/core/oss/pcm_oss.c:1252
 snd_pcm_plug_write_transfer+0x2b8/0x4a0 sound/core/oss/pcm_plugin.c:630
 snd_pcm_oss_write2 sound/core/oss/pcm_oss.c:1384 [inline]
 snd_pcm_oss_write1 sound/core/oss/pcm_oss.c:1450 [inline]
 snd_pcm_oss_write+0xbb5/0x1120 sound/core/oss/pcm_oss.c:2810
 vfs_write+0x288/0x940 fs/read_write.c:582
 ksys_write+0x147/0x250 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f61c578f749
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff33584288 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f61c59e5fa0 RCX: 00007f61c578f749
RDX: 00000000000005ce RSI: 0000200000000640 RDI: 0000000000000004
RBP: 00007f61c5813f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f61c59e5fa0 R14: 00007f61c59e5fa0 R15: 0000000000000003
 </TASK>

Allocated by task 5941:
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4e/0x70 mm/kasan/common.c:52
 ____kasan_kmalloc mm/kasan/common.c:374 [inline]
 __kasan_kmalloc+0x8f/0xa0 mm/kasan/common.c:383
 kasan_kmalloc include/linux/kasan.h:198 [inline]
 __do_kmalloc_node mm/slab_common.c:1007 [inline]
 __kmalloc+0xb4/0x240 mm/slab_common.c:1020
 data_ep_set_params sound/usb/endpoint.c:1263 [inline]
 snd_usb_endpoint_set_params+0x1575/0x28e0 sound/usb/endpoint.c:1395
 snd_usb_hw_params+0x123e/0x19c0 sound/usb/pcm.c:569
 snd_pcm_hw_params+0x835/0x1c50 sound/core/pcm_native.c:779
 snd_pcm_oss_change_params_locked+0x2144/0x3d30 sound/core/oss/pcm_oss.c:976
 snd_pcm_oss_make_ready_locked sound/core/oss/pcm_oss.c:1197 [inline]
 snd_pcm_oss_write1 sound/core/oss/pcm_oss.c:1415 [inline]
 snd_pcm_oss_write+0x2ff/0x1120 sound/core/oss/pcm_oss.c:2810
 vfs_write+0x288/0x940 fs/read_write.c:582
 ksys_write+0x147/0x250 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

The buggy address belongs to the object at ffff88801cf65800
 which belongs to the cache kmalloc-128 of size 128
The buggy address is located 0 bytes inside of
 allocated 120-byte region [ffff88801cf65800, ffff88801cf65878)

The buggy address belongs to the physical page:
page:ffffea000073d940 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1cf65
flags: 0xfff00000000800(slab|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000800 ffff8880178418c0 dead000000000122 0000000000000000
raw: 0000000000000000 0000000080100010 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 0x112cc0(GFP_USER|__GFP_NOWARN|__GFP_NORETRY), pid 5941, tgid 5941 (syz.0.17), ts 82818875675, free_ts 82785078839
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x1cd/0x210 mm/page_alloc.c:1554
 prep_new_page mm/page_alloc.c:1561 [inline]
 get_page_from_freelist+0x195c/0x19f0 mm/page_alloc.c:3191
 __alloc_pages+0x1e3/0x460 mm/page_alloc.c:4457
 alloc_slab_page+0x5d/0x170 mm/slub.c:1881
 allocate_slab mm/slub.c:2028 [inline]
 new_slab+0x87/0x2e0 mm/slub.c:2081
 ___slab_alloc+0xc6d/0x1300 mm/slub.c:3253
 __slab_alloc mm/slub.c:3339 [inline]
 __slab_alloc_node mm/slub.c:3392 [inline]
 slab_alloc_node mm/slub.c:3485 [inline]
 __kmem_cache_alloc_node+0x1a2/0x260 mm/slub.c:3534
 __do_kmalloc_node mm/slab_common.c:1006 [inline]
 __kmalloc+0xa4/0x240 mm/slab_common.c:1020
 kmalloc_array include/linux/slab.h:637 [inline]
 kcalloc include/linux/slab.h:668 [inline]
 constrain_params_by_rules sound/core/pcm_native.c:379 [inline]
 snd_pcm_hw_refine+0x97c/0x1620 sound/core/pcm_native.c:545
 snd_pcm_hw_param_mask sound/core/oss/pcm_oss.c:190 [inline]
 snd_pcm_oss_change_params_locked+0xa57/0x3d30 sound/core/oss/pcm_oss.c:897
 snd_pcm_oss_make_ready_locked sound/core/oss/pcm_oss.c:1197 [inline]
 snd_pcm_oss_write1 sound/core/oss/pcm_oss.c:1415 [inline]
 snd_pcm_oss_write+0x2ff/0x1120 sound/core/oss/pcm_oss.c:2810
 vfs_write+0x288/0x940 fs/read_write.c:582
 ksys_write+0x147/0x250 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1154 [inline]
 free_unref_page_prepare+0x7ce/0x8e0 mm/page_alloc.c:2336
 free_unref_page+0x32/0x2e0 mm/page_alloc.c:2429
 discard_slab mm/slub.c:2127 [inline]
 __unfreeze_partials+0x1cf/0x210 mm/slub.c:2667
 put_cpu_partial+0x17c/0x250 mm/slub.c:2743
 __slab_free+0x31d/0x410 mm/slub.c:3700
 qlink_free mm/kasan/quarantine.c:166 [inline]
 qlist_free_all+0x75/0xe0 mm/kasan/quarantine.c:185
 kasan_quarantine_reduce+0x143/0x160 mm/kasan/quarantine.c:292
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:305
 kasan_slab_alloc include/linux/kasan.h:188 [inline]
 slab_post_alloc_hook+0x6e/0x4d0 mm/slab.h:767
 slab_alloc_node mm/slub.c:3495 [inline]
 __kmem_cache_alloc_node+0x13e/0x260 mm/slub.c:3534
 kmalloc_trace+0x2a/0xe0 mm/slab_common.c:1098
 kmalloc include/linux/slab.h:600 [inline]
 gro_cells_destroy+0x2f9/0x3d0 net/core/gro_cells.c:125
 ip_tunnel_dev_free+0x19/0x60 net/ipv4/ip_tunnel.c:1044
 netdev_run_todo+0xbcd/0xd90 net/core/dev.c:10593
 ip_tunnel_delete_nets+0x321/0x360 net/ipv4/ip_tunnel.c:1158
 ops_exit_list net/core/net_namespace.c:178 [inline]
 cleanup_net+0x77f/0xb90 net/core/net_namespace.c:652

Memory state around the buggy address:
 ffff88801cf65700: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88801cf65780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88801cf65800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 fc
                                                                ^
 ffff88801cf65880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88801cf65900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 fc
==================================================================

Crashes (7):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/11/24 09:08 linux-6.6.y 0a805b6ea8cd 4fb8ef37 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-out-of-bounds Write in copy_to_urb
2026/02/16 01:17 linux-6.6.y 1b4ef5214f17 1e62d198 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-out-of-bounds Write in copy_to_urb
2026/01/31 08:32 linux-6.6.y 2cf6f68313dc c75a2f6e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-out-of-bounds Write in copy_to_urb
2026/01/31 08:32 linux-6.6.y 2cf6f68313dc c75a2f6e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-out-of-bounds Write in copy_to_urb
2025/11/24 09:50 linux-6.6.y 0a805b6ea8cd 4fb8ef37 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-out-of-bounds Write in copy_to_urb
2025/11/24 08:39 linux-6.6.y 0a805b6ea8cd 4fb8ef37 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-out-of-bounds Write in copy_to_urb
2025/11/24 08:39 linux-6.6.y 0a805b6ea8cd 4fb8ef37 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-out-of-bounds Write in copy_to_urb
* Struck through repros no longer work on HEAD.