9p: Unknown Cache mode or invalid value fscach 9pnet: Tag 65535 still in use ------------[ cut here ]------------ refcount_t: underflow; use-after-free. WARNING: CPU: 3 PID: 8169 at lib/refcount.c:28 refcount_warn_saturate+0x14a/0x210 lib/refcount.c:28 Modules linked in: CPU: 3 PID: 8169 Comm: syz-executor.2 Not tainted 6.9.0-rc4-syzkaller-00266-g977b1ef51866 #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 RIP: 0010:refcount_warn_saturate+0x14a/0x210 lib/refcount.c:28 Code: ff 89 de e8 f8 8e 10 fd 84 db 0f 85 66 ff ff ff e8 6b 94 10 fd c6 05 a5 5f 09 0b 01 90 48 c7 c7 e0 ba 6e 8b e8 17 69 d3 fc 90 <0f> 0b 90 90 e9 43 ff ff ff e8 48 94 10 fd 0f b6 1d 80 5f 09 0b 31 RSP: 0018:ffffc9000419f9c0 EFLAGS: 00010286 RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff81513b29 RDX: ffff88801b09a440 RSI: ffffffff81513b36 RDI: 0000000000000001 RBP: ffff88805abe7218 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000001 R12: ffffc9000419fa58 R13: ffff88805abe7218 R14: ffff88802996f000 R15: 1ffff92000833f43 FS: 0000000000000000(0000) GS:ffff88802c500000(0063) knlGS:00000000f5e8fb40 CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033 CR2: 0000000031e24000 CR3: 000000005b77a000 CR4: 0000000000350ef0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __refcount_sub_and_test include/linux/refcount.h:275 [inline] __refcount_dec_and_test include/linux/refcount.h:307 [inline] refcount_dec_and_test include/linux/refcount.h:325 [inline] p9_req_put+0x1f4/0x250 net/9p/client.c:401 p9_tag_cleanup net/9p/client.c:428 [inline] p9_client_destroy+0x22c/0x480 net/9p/client.c:1073 v9fs_session_init+0xba3/0x1a80 fs/9p/v9fs.c:490 v9fs_mount+0xc6/0xa90 fs/9p/vfs_super.c:122 legacy_get_tree+0x109/0x220 fs/fs_context.c:662 vfs_get_tree+0x8f/0x380 fs/super.c:1779 do_new_mount fs/namespace.c:3352 [inline] path_mount+0x6e1/0x1f10 fs/namespace.c:3679 do_mount fs/namespace.c:3692 [inline] __do_sys_mount fs/namespace.c:3898 [inline] __se_sys_mount fs/namespace.c:3875 [inline] __ia32_sys_mount+0x295/0x320 fs/namespace.c:3875 do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline] __do_fast_syscall_32+0x75/0x120 arch/x86/entry/common.c:321 do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:346 entry_SYSENTER_compat_after_hwframe+0x84/0x8e RIP: 0023:0xf729d579 Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00 RSP: 002b:00000000f5e8f5ac EFLAGS: 00000292 ORIG_RAX: 0000000000000015 RAX: ffffffffffffffda RBX: 00000000200001c0 RCX: 0000000020000480 RDX: 00000000200004c0 RSI: 0000000000000000 RDI: 0000000020000840 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000292 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 ---------------- Code disassembly (best guess), 2 bytes skipped: 0: 10 06 adc %al,(%rsi) 2: 03 74 b4 01 add 0x1(%rsp,%rsi,4),%esi 6: 10 07 adc %al,(%rdi) 8: 03 74 b0 01 add 0x1(%rax,%rsi,4),%esi c: 10 08 adc %cl,(%rax) e: 03 74 d8 01 add 0x1(%rax,%rbx,8),%esi 1e: 00 51 52 add %dl,0x52(%rcx) 21: 55 push %rbp 22: 89 e5 mov %esp,%ebp 24: 0f 34 sysenter 26: cd 80 int $0x80 * 28: 5d pop %rbp <-- trapping instruction 29: 5a pop %rdx 2a: 59 pop %rcx 2b: c3 ret 2c: 90 nop 2d: 90 nop 2e: 90 nop 2f: 90 nop 30: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi 37: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi