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Sun, 25 Oct 2026 04:46:48 -0700 (PDT) Date: Sun, 25 Oct 2026 04:46:48 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6addec28.412b1182.196980.00aa.GAE@google.com> Subject: [syzbot] [dm?] KASAN: null-ptr-deref Read in dm_kcopyd_client_destroy From: syzbot To: agk@redhat.com, bmarzins@redhat.com, dm-devel@lists.linux.dev, linux-kernel@vger.kernel.org, mpatocka@redhat.com, snitzer@kernel.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: 4169c9c90532 powerpc/irq: Fix build with CONFIG_PROC_FS=n git tree: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git console output: https://syzkaller.appspot.com/x/log.txt?x=126fa38e580000 kernel config: https://syzkaller.appspot.com/x/.config?x=e397d1e24d3cb03 dashboard link: https://syzkaller.appspot.com/bug?extid=a2626a25eb2595e3ec3c compiler: Debian clang version 22.1.8 (1~deb13u4), Debian LLD 22.1.8 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=166fa38e580000 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+a2626a25eb2595e3ec3c@syzkaller.appspotmail.com workqueue: Failed to create a rescuer kthread for wq "kcopyd": -EINTR ================================================================== BUG: KASAN: null-ptr-deref in instrument_atomic_read include/linux/instrumented.h:82 [inline] BUG: KASAN: null-ptr-deref in atomic_read include/linux/atomic/atomic-instrumented.h:32 [inline] BUG: KASAN: null-ptr-deref in dm_kcopyd_client_destroy+0xae/0x480 drivers/md/dm-kcopyd.c:980 Read of size 4 at addr 0000000000000174 by task syz.2.19/6560 CPU: 0 UID: 0 PID: 6560 Comm: syz.2.19 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/15/2026 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 kasan_report+0x117/0x150 mm/kasan/report.c:595 check_region_inline mm/kasan/generic.c:-1 [inline] kasan_check_range+0x264/0x2c0 mm/kasan/generic.c:200 instrument_atomic_read include/linux/instrumented.h:82 [inline] atomic_read include/linux/atomic/atomic-instrumented.h:32 [inline] dm_kcopyd_client_destroy+0xae/0x480 drivers/md/dm-kcopyd.c:980 __destroy+0x172/0x2f0 drivers/md/dm-cache-target.c:1973 cache_create drivers/md/dm-cache-target.c:2604 [inline] cache_ctr+0x1674/0x2bf0 drivers/md/dm-cache-target.c:2649 dm_table_add_target+0x58d/0xc70 drivers/md/dm-table.c:749 populate_table drivers/md/dm-ioctl.c:1602 [inline] table_load+0x325/0x8a0 drivers/md/dm-ioctl.c:1645 ctl_ioctl drivers/md/dm-ioctl.c:2221 [inline] dm_ctl_ioctl+0x9ec/0xe10 drivers/md/dm-ioctl.c:2243 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fb5b039f559 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:00007fb5b11ce028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007fb5b0626180 RCX: 00007fb5b039f559 RDX: 0000200000000280 RSI: 00000000c138fd09 RDI: 0000000000000004 RBP: 00007fb5b0436b20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fb5b0626218 R14: 00007fb5b0626180 R15: 00007fff197480a8 ================================================================== --- This report is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@googlegroups.com. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. If the report is already addressed, let syzbot know by replying with: #syz fix: exact-commit-title If you want syzbot to run the reproducer, reply with: #syz test: git://repo/address.git branch-or-commit-hash If you attach or paste a git patch, syzbot will apply it before testing. If you want to overwrite report's subsystems, reply with: #syz set subsystems: new-subsystem (See the list of subsystem names on the web dashboard) If the report is a duplicate of another one, reply with: #syz dup: exact-subject-of-another-report If you want to undo deduplication, reply with: #syz undup