syzbot


KASAN: slab-use-after-free Read in vhci_tx_loop

Status: upstream: reported on 2025/12/22 02:03
Subsystems: usb
[Documentation on labels]
Reported-by: syzbot+549021d06a2b557303bd@syzkaller.appspotmail.com
First crash: 156d, last: 7d20h
✨ AI Jobs (2)
ID Workflow Result Correct Bug Created Started Finished Revision Error
9f043f06-78ac-4612-9076-18d640dc00cf assessment-security 💥 KASAN: slab-use-after-free Read in vhci_tx_loop 2026/05/14 14:40 2026/05/14 14:40 2026/05/14 14:42 6ccb967e465e832a7bfd7a116ad00d52a0923a5d failed to run ["make" "KERNELVERSION=syzkaller" "KERNELRELEASE=syzkaller" "LOCALVERSION=-syzkaller" "-j" "32" "ARCH=x86_64" "CC=ccache clang" "LD=ld.lld" "O=/app/workdir/cache/build/ea6319647410b1260ea344b6710ec8b631a15462" "-s" "bzImage" "compile_commands.json"]: exit status 2 Root cause: error: unable to open output file 'kernel/rcu/update.o': 'No such file or directory' /app/workdir/cache/src/fdb7cb6bb7b27f7e6d7ef669765813dd83c15406/lib/maple_tree.c:3514:20: warning: stack frame size (2424) exceeds limit (2048) in 'mas_wr_store_entry' [-Wframe-larger-than] 3514 | static inline void mas_wr_store_entry(struct ma_wr_state *wr_mas) | ^ 1 warning generated. /app/workdir/cache/src/fdb7cb6bb7b27f7e6d7ef669765813dd83c15406/sound/usb/mixer_s1810c.c:634:5: warning: stack frame size (2360) exceeds limit (2048) in 'snd_sc1810_init_mixer' [-Wframe-larger-than] 634 | int snd_sc1810_init_mixer(struct usb_mixer_interface *mixer) | ^ 1 warning generated. fixdep: not all data was written to the output make[6]: *** [/app/workdir/cache/src/fdb7cb6bb7b27f7e6d7ef669765813dd83c15406/scripts/Makefile.build:289: sound/hda/core/device.o] Error 1 make[6]: *** Deleting file 'sound/hda/core/device.o' make[5]: *** [/app/workdir/cache/src/fdb7cb6bb7b27f7e6d7ef669765813dd83c15406/scripts/Makefile.build:548: sound/hda/core] Error 2 make[5]: *** Waiting for unfinished jobs.... fatal error: error in backend: IO failure on output stream: No space left on device PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace, preprocessed source, and associated run script. Stack dump: 0. Program arguments: /usr/bin/clang --target=x86_64-linux-gnu -fintegrated-as -Werror=unknown-warning-option -Werror=ignored-optimization-argument -Werror=option-ignored -Werror=unused-command-line-argument -fmacro-prefix-map=/app/workdir/cache/src/fdb7cb6bb7b27f7e6d7ef669765813dd83c15406/= -fshort-wchar -funsigned-char -fno-common -fno-PIE -fno-strict-aliasing -std=gnu11 -fms-extensions -Wno-gnu -Wno-microsoft-anon-tag -mno-sse -mno-mmx -mno-sse2 -mno-3dnow -mno-avx -mno-sse4a -fcf-protection=branch -fno-jump-tables -m64 -falign-loops=1 -mno-80387 -mno-fp-ret-in-387 -mstack-alignment=8 -mskip-rax-setup -march=x86-64 -mtune=generic -mno-red-zone -mcmodel=kernel -mstack-protector-guard-reg=gs -mstack-protector-guard-symbol=__ref_stack_chk_guard -Wno-sign-compare -fno-asynchronous-unwind-tables -mretpoline-external-thunk -mindirect-branch-cs-prefix -mfunction-return=thunk-extern -fpatchable-function-entry=16,16 -fno-delete-null-pointer-checks -O2 -fstack-protector-strong -fomit-frame-pointer -ftrivial-auto-var-init=zero -fno-stack-clash-protection -falign-functions=16 -fstrict-flex-arrays=3 -fno-strict-overflow -fno-stack-check -fno-builtin-wcslen -Wall -Wextra -Wundef -Werror=implicit-function-declaration -Werror=implicit-int -Werror=return-type -Werror=strict-prototypes -Wno-format-security -Wno-trigraphs -Wno-frame-address -Wno-address-of-packed-member -Wmissing-declarations -Wmissing-prototypes -Wframe-larger-than=2048 -Wno-format-overflow-non-kprintf -Wno-format-truncation-non-kprintf -Wno-default-const-init-unsafe -Wno-type-limits -Wno-pointer-sign -Wcast-function-type -Wno-unterminated-string-initialization -Wimplicit-fallthrough -Werror=date-time -Werror=incompatible-pointer-types -Wenum-conversion -Wunused -Wno-unused-but-set-variable -Wno-unused-const-variable -Wno-format-overflow -Wno-override-init -Wno-pointer-to-enum-cast -Wno-tautological-constant-out-of-range-compare -Wno-unaligned-access -Wno-enum-compare-conditional -Wno-missing-field-initializers -Wno-shift-negative-value -Wno-enum-enum-conversion -Wno-sign-compare -Wno-unused-parameter -g -gdwarf-4 -fsanitize=kernel-address -mllvm -asan-mapping-offset=0xdffffc0000000000 -mllvm -asan-instrumentation-with-call-threshold=10000 -mllvm -asan-stack=1 -mllvm -asan-globals=1 -mllvm -asan-kernel-mem-intrinsic-prefix=1 -fsanitize=array-bounds -fsanitize=shift -fsanitize-coverage=trace-pc -fsanitize-coverage=trace-cmp -fdebug-info-for-p
a22cff4a-a72a-4885-8b1e-285a4b367ef5 repro KASAN: slab-use-after-free Read in vhci_tx_loop 2026/03/06 21:56 2026/03/06 21:56 2026/03/06 22:06 31e9c887f7dc24e04b3ca70d0d54fc34141844b0
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [usb?] KASAN: slab-use-after-free Read in vhci_tx_loop 0 (1) 2025/12/22 02:03
Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream general protection fault in vhci_tx_loop usb 2 1 510d 506d 0/29 auto-obsoleted due to no activity on 2025/03/28 12:39
linux-5.15 KASAN: use-after-free Read in vhci_tx_loop 19 1 417d 417d 0/3 auto-obsoleted due to no activity on 2025/07/09 17:53

Sample crash report:
==================================================================
BUG: KASAN: slab-use-after-free in vhci_send_cmd_submit drivers/usb/usbip/vhci_tx.c:69 [inline]
BUG: KASAN: slab-use-after-free in vhci_tx_loop+0x3e9/0x1c50 drivers/usb/usbip/vhci_tx.c:241
Read of size 8 at addr ffff888025a4b720 by task vhci_tx/16998

CPU: 1 UID: 0 PID: 16998 Comm: vhci_tx Tainted: G             L      syzkaller #0 PREEMPT_{RT,(full)} 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
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
 vhci_send_cmd_submit drivers/usb/usbip/vhci_tx.c:69 [inline]
 vhci_tx_loop+0x3e9/0x1c50 drivers/usb/usbip/vhci_tx.c:241
 kthread+0x388/0x470 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
 </TASK>

Allocated by task 9:
 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]
 __kmalloc_cache_noprof+0x3a6/0x690 mm/slub.c:5419
 kmalloc_noprof include/linux/slab.h:950 [inline]
 kzalloc_noprof include/linux/slab.h:1188 [inline]
 vhci_tx_urb drivers/usb/usbip/vhci_hcd.c:674 [inline]
 vhci_urb_enqueue+0x5c9/0xe10 drivers/usb/usbip/vhci_hcd.c:829
 usb_hcd_submit_urb+0x323/0x1b50 drivers/usb/core/hcd.c:1542
 usb_start_wait_urb+0x13f/0x5b0 drivers/usb/core/message.c:62
 usb_internal_control_msg drivers/usb/core/message.c:117 [inline]
 usb_control_msg+0x234/0x3e0 drivers/usb/core/message.c:167
 get_bMaxPacketSize0 drivers/usb/core/hub.c:4851 [inline]
 hub_port_init+0xb1e/0x28c0 drivers/usb/core/hub.c:5047
 hub_port_connect drivers/usb/core/hub.c:5496 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5707 [inline]
 port_event drivers/usb/core/hub.c:5871 [inline]
 hub_event+0x25d3/0x4f60 drivers/usb/core/hub.c:5953
 process_one_work kernel/workqueue.c:3302 [inline]
 process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3385
 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3466
 kthread+0x388/0x470 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 16997:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 kasan_save_free_info+0x46/0x50 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:2689 [inline]
 slab_free mm/slub.c:6250 [inline]
 kfree+0x1c5/0x6c0 mm/slub.c:6565
 pickup_urb_and_free_priv+0x225/0x3f0 drivers/usb/usbip/vhci_rx.c:46
 vhci_recv_ret_submit drivers/usb/usbip/vhci_rx.c:65 [inline]
 vhci_rx_pdu drivers/usb/usbip/vhci_rx.c:242 [inline]
 vhci_rx_loop+0x3c5/0xa00 drivers/usb/usbip/vhci_rx.c:265
 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 ffff888025a4b700
 which belongs to the cache kmalloc-64 of size 64
The buggy address is located 32 bytes inside of
 freed 64-byte region [ffff888025a4b700, ffff888025a4b740)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x25a4b
flags: 0x80000000000000(node=0|zone=1)
page_type: f5(slab)
raw: 0080000000000000 ffff88801a0108c0 dead000000000100 dead000000000122
raw: 0000000000000000 0000000800200020 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 0xd2c40(GFP_NOFS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 21068060516, free_ts 21067304845
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x231/0x280 mm/page_alloc.c:1858
 prep_new_page mm/page_alloc.c:1866 [inline]
 get_page_from_freelist+0x27c8/0x2840 mm/page_alloc.c:3946
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5226
 alloc_slab_page mm/slub.c:3278 [inline]
 allocate_slab+0x77/0x660 mm/slub.c:3467
 new_slab mm/slub.c:3525 [inline]
 refill_objects+0x33c/0x3d0 mm/slub.c:7255
 refill_sheaf mm/slub.c:2816 [inline]
 __pcs_replace_empty_main+0x373/0x720 mm/slub.c:4651
 alloc_from_pcs mm/slub.c:4749 [inline]
 slab_alloc_node mm/slub.c:4883 [inline]
 __do_kmalloc_node mm/slub.c:5294 [inline]
 __kmalloc_noprof+0x530/0x7b0 mm/slub.c:5307
 kmalloc_noprof include/linux/slab.h:954 [inline]
 kzalloc_noprof include/linux/slab.h:1188 [inline]
 tomoyo_get_name+0x20c/0x590 security/tomoyo/memory.c:173
 tomoyo_parse_name_union+0xd9/0x130 security/tomoyo/util.c:260
 tomoyo_update_mount_acl+0xe9/0x2d0 security/tomoyo/file.c:995
 tomoyo_write_file+0xae4/0xc50 security/tomoyo/file.c:1048
 tomoyo_write_domain2 security/tomoyo/common.c:1160 [inline]
 tomoyo_add_entry security/tomoyo/common.c:2177 [inline]
 tomoyo_supervisor+0x1208/0x1570 security/tomoyo/common.c:2238
 tomoyo_audit_mount_log security/tomoyo/mount.c:33 [inline]
 tomoyo_mount_acl security/tomoyo/mount.c:168 [inline]
 tomoyo_mount_permission+0x624/0x9d0 security/tomoyo/mount.c:239
 security_sb_mount+0xe4/0x320 security/security.c:1088
 path_mount+0xbc/0x10e0 fs/namespace.c:4096
 init_mount+0xc3/0x110 fs/init.c:42
page last free pid 1 tgid 1 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1402 [inline]
 free_unref_folios+0xc50/0x1970 mm/page_alloc.c:3004
 folios_put_refs+0x7cb/0x8d0 mm/swap.c:1008
 folio_batch_release include/linux/folio_batch.h:101 [inline]
 truncate_inode_pages_range+0x3e0/0xe30 mm/truncate.c:408
 kill_bdev block/bdev.c:91 [inline]
 blkdev_flush_mapping+0x10c/0x2f0 block/bdev.c:720
 blkdev_put_whole block/bdev.c:727 [inline]
 bdev_release+0x422/0x660 block/bdev.c:1152
 blkdev_release+0x15/0x20 block/fops.c:705
 __fput+0x461/0xa70 fs/file_table.c:510
 task_work_run+0x1d9/0x270 kernel/task_work.c:233
 init_flush_fput init/do_mounts.h:41 [inline]
 mount_root_generic+0x1bf/0x450 init/do_mounts.c:205
 prepare_namespace+0x66/0xc0 init/do_mounts.c:484
 kernel_init_freeable+0x2ee/0x3e0 init/main.c:1721
 kernel_init+0x1d/0x1d0 init/main.c:1593
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Memory state around the buggy address:
 ffff888025a4b600: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff888025a4b680: 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc
>ffff888025a4b700: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
                               ^
 ffff888025a4b780: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff888025a4b800: 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc
==================================================================

Crashes (13):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/05/14 09:00 upstream e1914add2799 6ccb967e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root KASAN: slab-use-after-free Read in vhci_tx_loop
2026/05/06 08:18 upstream 9207d47f966b 26da2c66 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root KASAN: slab-use-after-free Read in vhci_tx_loop
2026/04/17 17:38 upstream 43cfbdda5af6 24ecfc1e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root KASAN: slab-use-after-free Read in vhci_tx_loop
2025/12/31 01:00 upstream dbf8fe85a16a d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root KASAN: slab-use-after-free Read in vhci_tx_loop
2025/12/17 19:07 upstream ea1013c15392 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root KASAN: slab-use-after-free Read in vhci_tx_loop
2026/05/15 01:19 linux-next e98d21c170b0 6ccb967e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root KASAN: slab-use-after-free Read in vhci_tx_loop
2026/05/08 16:31 linux-next e98d21c170b0 5633175a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root KASAN: slab-use-after-free Read in vhci_tx_loop
2026/05/07 17:12 linux-next 17c7841d09ee e358bca5 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root KASAN: slab-use-after-free Read in vhci_tx_loop
2026/04/21 06:59 linux-next 97e797263a5e 3f2e655b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root KASAN: slab-use-after-free Read in vhci_tx_loop
2026/05/15 00:53 linux-next e98d21c170b0 6ccb967e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce general protection fault in vhci_tx_loop
2026/05/14 20:16 linux-next e98d21c170b0 6ccb967e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce general protection fault in vhci_tx_loop
2026/05/08 18:44 linux-next e98d21c170b0 0c5a8d8f .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root general protection fault in vhci_tx_loop
2026/01/15 07:10 linux-next 9b7977f9e39b d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce general protection fault in vhci_tx_loop
* Struck through repros no longer work on HEAD.