Hello, syzbot found the following issue on: HEAD commit: d07de43e3f05 Merge tag 'io_uring-6.14-20250321' of git://g.. git tree: upstream console+strace: https://syzkaller.appspot.com/x/log.txt?x=14223004580000 kernel config: https://syzkaller.appspot.com/x/.config?x=620facf12ff15d10 dashboard link: https://syzkaller.appspot.com/bug?extid=cf285a028ffba71b2ef5 compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16be1c4c580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12223004580000 Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/a241563b93db/disk-d07de43e.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/6c435395db14/vmlinux-d07de43e.xz kernel image: https://storage.googleapis.com/syzbot-assets/59fc4b510cae/bzImage-d07de43e.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+cf285a028ffba71b2ef5@xxxxxxxxxxxxxxxxxxxxxxxxx ------------[ cut here ]------------ refcount_t: underflow; use-after-free. WARNING: CPU: 0 PID: 5823 at lib/refcount.c:28 refcount_warn_saturate+0x15a/0x1d0 lib/refcount.c:28 Modules linked in: CPU: 0 UID: 0 PID: 5823 Comm: syz-executor232 Not tainted 6.14.0-rc7-syzkaller-00186-gd07de43e3f05 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 RIP: 0010:refcount_warn_saturate+0x15a/0x1d0 lib/refcount.c:28 Code: c0 e1 7f 8c e8 d7 bc 93 fc 90 0f 0b 90 90 eb 99 e8 6b 01 d4 fc c6 05 97 15 38 0b 01 90 48 c7 c7 20 e2 7f 8c e8 b7 bc 93 fc 90 <0f> 0b 90 90 e9 76 ff ff ff e8 48 01 d4 fc c6 05 71 15 38 0b 01 90 RSP: 0018:ffffc90003e8f9c0 EFLAGS: 00010246 RAX: bae32b5aa58f9a00 RBX: ffff88807f4ad8d0 RCX: ffff888034e08000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000003 R08: ffffffff81819d62 R09: fffffbfff1d3a69c R10: dffffc0000000000 R11: fffffbfff1d3a69c R12: dffffc0000000000 R13: 1ffff11005aa3f80 R14: 1ffff1100fe95af6 R15: ffff88807f4ad7b0 FS: 000055557c8ba480(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000020000000022c CR3: 000000003574c000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> io_notif_flush io_uring/notif.h:40 [inline] io_send_zc_cleanup+0x121/0x170 io_uring/net.c:1222 io_clean_op+0x58c/0x9a0 io_uring/io_uring.c:406 io_free_batch_list io_uring/io_uring.c:1429 [inline] __io_submit_flush_completions+0xc16/0xd20 io_uring/io_uring.c:1470 io_submit_flush_completions io_uring/io_uring.h:159 [inline] ctx_flush_and_put io_uring/io_uring.c:1031 [inline] io_handle_tw_list+0x473/0x500 io_uring/io_uring.c:1071 tctx_task_work_run+0x9a/0x370 io_uring/io_uring.c:1123 tctx_task_work+0x9a/0x100 io_uring/io_uring.c:1141 task_work_run+0x24f/0x310 kernel/task_work.c:227 ptrace_notify+0x2d9/0x380 kernel/signal.c:2522 ptrace_report_syscall include/linux/ptrace.h:415 [inline] ptrace_report_syscall_exit include/linux/ptrace.h:477 [inline] syscall_exit_work+0xc7/0x1d0 kernel/entry/common.c:173 syscall_exit_to_user_mode_prepare kernel/entry/common.c:200 [inline] __syscall_exit_to_user_mode_work kernel/entry/common.c:205 [inline] syscall_exit_to_user_mode+0x24a/0x340 kernel/entry/common.c:218 do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fda97775569 Code: 48 83 c4 28 c3 e8 37 17 00 00 0f 1f 80 00 00 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 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffe9ef18ea8 EFLAGS: 00000216 ORIG_RAX: 00000000000001aa RAX: 0000000000001000 RBX: 0000000000000007 RCX: 00007fda97775569 RDX: 0000000000000000 RSI: 00000000000047bc RDI: 0000000000000007 RBP: 0000200000000480 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000021 R11: 0000000000000216 R12: 000000000000081f R13: 00002000000000c0 R14: 0000000000000001 R15: 0000000000000001 </TASK> --- 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@xxxxxxxxxxxxxxxx. 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
