BUG: please report to dccp@vger.kernel.org => prev = 0, last = 0 at net/dccp/ccids/lib/packet_history.c:417/tfrc_rx_hist_sample_rtt() CPU: 0 PID: 9927 Comm: syz.2.1998 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/30/2025 Call trace: dump_backtrace+0x0/0x43c arch/arm64/kernel/stacktrace.c:152 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216 __dump_stack+0x30/0x40 lib/dump_stack.c:88 dump_stack_lvl+0xf8/0x160 lib/dump_stack.c:106 dump_stack+0x1c/0x5c lib/dump_stack.c:113 tfrc_rx_hist_sample_rtt+0x318/0x3ec net/dccp/ccids/lib/packet_history.c:414 ccid3_hc_rx_packet_recv+0x51c/0xb24 net/dccp/ccids/ccid3.c:760 ccid_hc_rx_packet_recv net/dccp/ccid.h:182 [inline] dccp_deliver_input_to_ccids net/dccp/input.c:176 [inline] dccp_rcv_established+0x1ac/0x2d8 net/dccp/input.c:374 dccp_v4_do_rcv+0xa8/0x184 net/dccp/ipv4.c:672 sk_backlog_rcv include/net/sock.h:1061 [inline] __release_sock+0x19c/0x3a0 net/core/sock.c:2725 release_sock+0x60/0x258 net/core/sock.c:3266 dccp_sendmsg+0x494/0x8a8 net/dccp/proto.c:812 inet_sendmsg+0x154/0x284 net/ipv4/af_inet.c:834 sock_sendmsg_nosec net/socket.c:704 [inline] __sock_sendmsg net/socket.c:716 [inline] sock_write_iter+0x23c/0x31c net/socket.c:1079 call_write_iter include/linux/fs.h:2172 [inline] new_sync_write fs/read_write.c:507 [inline] vfs_write+0x7c8/0xa2c fs/read_write.c:594 ksys_write+0x120/0x210 fs/read_write.c:647 __do_sys_write fs/read_write.c:659 [inline] __se_sys_write fs/read_write.c:656 [inline] __arm64_sys_write+0x7c/0x90 fs/read_write.c:656 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181 el0_svc+0x78/0x1e0 arch/arm64/kernel/entry-common.c:608 el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584