syzbot


KASAN: vmalloc-out-of-bounds Read in kcov_remote_stop

Status: upstream: reported on 2025/10/07 03:33
Subsystems: usb
[Documentation on labels]
Reported-by: syzbot+90984d3713722683112e@syzkaller.appspotmail.com
First crash: 4d04h, last: 8h32m
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [usb?] KASAN: vmalloc-out-of-bounds Read in kcov_remote_stop 0 (1) 2025/10/07 03:33
Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KMSAN: uninit-value in exit_to_user_mode_loop (3) kernel 7 C 2558 1210d 1469d 0/29 auto-closed as invalid on 2022/09/22 19:06

Sample crash report:
usb 5-1: config 0 descriptor??
appletouch 5-1:0.85: Failed to read mode from device.
appletouch 5-1:0.85: probe with driver appletouch failed with error -5
usb 5-1: USB disconnect, device number 31
==================================================================
BUG: KASAN: vmalloc-out-of-bounds in __list_add_valid_or_report+0x4e/0x130 lib/list_debug.c:29
Read of size 8 at addr ffffc9000ffa1008 by task kworker/1:1/44

CPU: 1 UID: 0 PID: 44 Comm: kworker/1:1 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Workqueue: usb_hub_wq hub_event
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xca/0x240 mm/kasan/report.c:482
 kasan_report+0x118/0x150 mm/kasan/report.c:595
 __list_add_valid_or_report+0x4e/0x130 lib/list_debug.c:29
 __list_add_valid include/linux/list.h:96 [inline]
 __list_add include/linux/list.h:158 [inline]
 list_add include/linux/list.h:177 [inline]
 kcov_remote_area_put kernel/kcov.c:156 [inline]
 kcov_remote_stop+0x52d/0x660 kernel/kcov.c:1060
 hub_event+0x45d2/0x4a20 drivers/usb/core/hub.c:5997
 process_one_work kernel/workqueue.c:3263 [inline]
 process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3346
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3427
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x439/0x7d0 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

The buggy address belongs to a vmalloc virtual mapping
Memory state around the buggy address:
 ffffc9000ffa0f00: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
 ffffc9000ffa0f80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
>ffffc9000ffa1000: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
                      ^
 ffffc9000ffa1080: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
 ffffc9000ffa1100: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
==================================================================

Crashes (7):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/10/06 23:36 upstream fd94619c4336 91305dbe .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root KASAN: vmalloc-out-of-bounds Read in kcov_remote_stop
2025/10/04 22:51 upstream cbf33b8e0b36 49379ee0 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root KASAN: vmalloc-out-of-bounds Read in kcov_remote_stop
2025/10/04 14:56 upstream cbf33b8e0b36 49379ee0 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root KASAN: vmalloc-out-of-bounds Read in kcov_remote_stop
2025/10/03 22:18 upstream 9b0d551bcc05 49379ee0 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root KASAN: vmalloc-out-of-bounds Read in kcov_remote_stop
2025/10/03 04:55 upstream e406d57be7bd 49379ee0 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root KASAN: vmalloc-out-of-bounds Read in kcov_remote_stop
2025/10/03 03:32 upstream 7f7072574127 49379ee0 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root KASAN: vmalloc-out-of-bounds Read in kcov_remote_stop
2025/10/06 14:32 upstream fd94619c4336 91305dbe .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root BUG: corrupted list in kcov_remote_stop
* Struck through repros no longer work on HEAD.