------------[ cut here ]------------ refcount_t: addition on 0; use-after-free. WARNING: CPU: 2 PID: 31702 at lib/refcount.c:25 refcount_warn_saturate+0x1ca/0x210 lib/refcount.c:25 Modules linked in: CPU: 2 PID: 31702 Comm: syz-executor.3 Not tainted 6.7.0-rc6-syzkaller-00044-g1a44b0073b92 #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 58 a3 25 fd 84 db 0f 85 e6 fe ff ff e8 1b a8 25 fd c6 05 9a 88 a1 0a 01 90 48 c7 c7 00 9d 2e 8b e8 b7 ec eb fc 90 <0f> 0b 90 90 e9 c3 fe ff ff e8 f8 a7 25 fd c6 05 75 88 a1 0a 01 90 RSP: 0018:ffffc900296df850 EFLAGS: 00010286 RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffc9002c40a000 RDX: 0000000000040000 RSI: ffffffff814db526 RDI: 0000000000000001 RBP: ffffffff92b5b7b0 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000002 R12: 0000000000000010 R13: ffffffff92b5b7b0 R14: 0000000000000001 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff88802c800000(0063) knlGS:00000000f7efdb40 CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033 CR2: 00000000f7354000 CR3: 0000000050ee3000 CR4: 0000000000350ef0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __refcount_add include/linux/refcount.h:199 [inline] __refcount_inc include/linux/refcount.h:250 [inline] refcount_inc include/linux/refcount.h:267 [inline] kref_get include/linux/kref.h:45 [inline] tcp_sigpool_alloc_ahash+0x9cb/0xce0 net/ipv4/tcp_sigpool.c:166 tcp_md5_alloc_sigpool+0x1b/0x40 net/ipv4/tcp.c:4379 tcp_md5_do_add+0x192/0x460 net/ipv4/tcp_ipv4.c:1403 tcp_v6_parse_md5_keys+0x68d/0x860 net/ipv6/tcp_ipv6.c:676 do_tcp_setsockopt+0x1302/0x2880 net/ipv4/tcp.c:3644 tcp_setsockopt+0xd4/0x100 net/ipv4/tcp.c:3726 do_sock_setsockopt+0x222/0x470 net/socket.c:2311 __sys_setsockopt+0x1a6/0x270 net/socket.c:2334 __do_sys_setsockopt net/socket.c:2343 [inline] __se_sys_setsockopt net/socket.c:2340 [inline] __ia32_sys_setsockopt+0xbc/0x150 net/socket.c:2340 do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline] __do_fast_syscall_32+0x62/0xe0 arch/x86/entry/common.c:321 do_fast_syscall_32+0x33/0x70 arch/x86/entry/common.c:346 entry_SYSENTER_compat_after_hwframe+0x70/0x7a RIP: 0023:0xf7f02579 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:00000000f7efd5ac EFLAGS: 00000292 ORIG_RAX: 000000000000016e RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000000006 RDX: 000000000000000e RSI: 0000000020000000 RDI: 00000000000000d8 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