------------[ cut here ]------------ refcount_t: underflow; use-after-free. WARNING: CPU: 1 PID: 5129 at lib/refcount.c:28 refcount_warn_saturate+0x103/0x1f0 lib/refcount.c:28 Modules linked in: CPU: 1 PID: 5129 Comm: syz-executor.0 Not tainted 5.10.235 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 RIP: 0010:refcount_warn_saturate+0x103/0x1f0 lib/refcount.c:28 Code: 1d 6f ee 71 03 31 ff 89 de e8 29 5b 4d ff 84 db 75 a3 e8 10 62 4d ff 48 c7 c7 20 c8 5b 84 c6 05 4f ee 71 03 01 e8 9d be e6 01 <0f> 0b eb 87 e8 f4 61 4d ff 0f b6 1d 38 ee 71 03 31 ff 89 de e8 f4 RSP: 0018:ffff8880170379b0 EFLAGS: 00010286 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000040000 RSI: ffffffff8129e973 RDI: ffffed1002e06f28 RBP: ffff888046024008 R08: 0000000000000001 R09: ffff88806cf37b0f R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000000 R13: ffff888046024008 R14: ffff88800cbc4010 R15: 0000000000000000 FS: 00007f1c2f3cb700(0000) GS:ffff88806cf00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f1c2f3aa718 CR3: 0000000046d96000 CR4: 0000000000350ee0 Call Trace: __refcount_sub_and_test include/linux/refcount.h:283 [inline] __refcount_dec_and_test include/linux/refcount.h:315 [inline] refcount_dec_and_test include/linux/refcount.h:333 [inline] kref_put include/linux/kref.h:64 [inline] p9_req_put+0x1ad/0x210 net/9p/client.c:389 p9_conn_destroy net/9p/trans_fd.c:901 [inline] p9_fd_close+0x267/0x4a0 net/9p/trans_fd.c:934 p9_client_create+0x8f3/0x1230 net/9p/client.c:1083 v9fs_session_init+0x1dd/0x1680 fs/9p/v9fs.c:406 v9fs_mount+0x79/0x8f0 fs/9p/vfs_super.c:126 legacy_get_tree+0x105/0x220 fs/fs_context.c:593 vfs_get_tree+0x8e/0x300 fs/super.c:1572 do_new_mount fs/namespace.c:2917 [inline] path_mount+0x1429/0x2120 fs/namespace.c:3247 do_mount fs/namespace.c:3260 [inline] __do_sys_mount fs/namespace.c:3468 [inline] __se_sys_mount fs/namespace.c:3445 [inline] __x64_sys_mount+0x282/0x300 fs/namespace.c:3445 do_syscall_64+0x33/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x67/0xd1 RIP: 0033:0x7f1c31e76b19 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 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f1c2f3cb188 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 00007f1c31f8a020 RCX: 00007f1c31e76b19 RDX: 00000000200000c0 RSI: 0000000020000040 RDI: 0000000000000000 RBP: 00007f1c31ed0f6d R08: 0000000020000280 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffd6a320dbf R14: 00007f1c2f3cb300 R15: 0000000000022000 irq event stamp: 1017 hardirqs last enabled at (1027): [] console_unlock+0x92d/0xb40 kernel/printk/printk.c:2567 hardirqs last disabled at (1416): [] console_unlock+0x839/0xb40 kernel/printk/printk.c:2482 softirqs last enabled at (1514): [] asm_call_irq_on_stack+0x12/0x20 softirqs last disabled at (1425): [] asm_call_irq_on_stack+0x12/0x20 ---[ end trace 699a6114fca334d9 ]--- perf: interrupt took too long (8183 > 8148), lowering kernel.perf_event_max_sample_rate to 24000 perf: interrupt took too long (10258 > 10228), lowering kernel.perf_event_max_sample_rate to 19000 perf: interrupt took too long (12831 > 12822), lowering kernel.perf_event_max_sample_rate to 15000