------------[ cut here ]------------ refcount_t: addition on 0; use-after-free. WARNING: CPU: 0 PID: 5920 at lib/refcount.c:25 refcount_warn_saturate+0x1ca/0x210 lib/refcount.c:25 Modules linked in: CPU: 0 PID: 5920 Comm: syz-executor.1 Not tainted 6.9.0-rc2-syzkaller-00080-gc85af715cac0 #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+0x1ca/0x210 lib/refcount.c:25 Code: ff 89 de e8 18 4c 12 fd 84 db 0f 85 e6 fe ff ff e8 8b 51 12 fd c6 05 81 33 0d 0b 01 90 48 c7 c7 40 b5 6e 8b e8 e7 24 d5 fc 90 <0f> 0b 90 90 e9 c3 fe ff ff e8 68 51 12 fd c6 05 5c 33 0d 0b 01 90 RSP: 0018:ffffc900039ff888 EFLAGS: 00010286 RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff8150eb59 RDX: ffff88801b9e0000 RSI: ffffffff8150eb66 RDI: 0000000000000001 RBP: ffff88805d14870c R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000002 R12: ffff88805d14870c R13: dffffc0000000000 R14: 1ffff9200073ff15 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff88802c200000(0063) knlGS:00000000f5ebdb40 CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033 CR2: 00000000576a2480 CR3: 0000000058836000 CR4: 0000000000352ef0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __refcount_add include/linux/refcount.h:190 [inline] __refcount_inc include/linux/refcount.h:241 [inline] refcount_inc include/linux/refcount.h:258 [inline] p9_fid_get include/net/9p/client.h:262 [inline] v9fs_fid_find+0x2e2/0x330 fs/9p/fid.c:129 v9fs_fid_lookup_with_uid fs/9p/fid.c:181 [inline] v9fs_fid_lookup+0xd8/0xf20 fs/9p/fid.c:314 v9fs_fid_clone fs/9p/fid.h:29 [inline] v9fs_file_open+0x5f0/0xba0 fs/9p/vfs_file.c:56 do_dentry_open+0x8da/0x18c0 fs/open.c:955 do_open fs/namei.c:3642 [inline] path_openat+0x1dfb/0x2990 fs/namei.c:3799 do_filp_open+0x1dc/0x430 fs/namei.c:3826 do_sys_openat2+0x17a/0x1e0 fs/open.c:1406 do_sys_open fs/open.c:1421 [inline] __do_sys_creat fs/open.c:1497 [inline] __se_sys_creat fs/open.c:1491 [inline] __ia32_sys_creat+0xcc/0x120 fs/open.c:1491 do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline] __do_fast_syscall_32+0x7a/0x120 arch/x86/entry/common.c:321 do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:346 entry_SYSENTER_compat_after_hwframe+0x7f/0x89 RIP: 0023:0xf72e4579 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:00000000f5ebd5ac EFLAGS: 00000292 ORIG_RAX: 0000000000000008 RAX: ffffffffffffffda RBX: 0000000020000040 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 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