Liu Jian d900f3d20c bpf, sockmap: Fix an infinite loop error when len is 0 in tcp_bpf_recvmsg_parser() ... When the buffer length of the recvmsg system call is 0, we got the flollowing soft lockup problem: watchdog: BUG: soft lockup - CPU#3 stuck for 27s! [a.out:6149] CPU: 3 PID: 6149 Comm: a.out Kdump: loaded Not tainted 6.2.0+ #30 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.15.0-1 04/01/2014 RIP: 0010:remove_wait_queue+0xb/0xc0 Code: 5e 41 5f c3 cc cc cc cc 0f 1f 80 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 0f 1f 44 00 00 41 57 <41> 56 41 55 41 54 55 48 89 fd 53 48 89 f3 4c 8d 6b 18 4c 8d 73 20 RSP: 0018:ffff88811b5978b8 EFLAGS: 00000246 RAX: 0000000000000000 RBX: ffff88811a7d3780 RCX: ffffffffb7a4d768 RDX: dffffc0000000000 RSI: ffff88811b597908 RDI: ffff888115408040 RBP: 1ffff110236b2f1b R08: 0000000000000000 R09: ffff88811a7d37e7 R10: ffffed10234fa6fc R11: 0000000000000001 R12: ffff88811179b800 R13: 0000000000000001 R14: ffff88811a7d38a8 R15: ffff88811a7d37e0 FS: 00007f6fb5398740(0000) GS:ffff888237180000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000020000000 CR3: 000000010b6ba002 CR4: 0000000000370ee0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> tcp_msg_wait_data+0x279/0x2f0 tcp_bpf_recvmsg_parser+0x3c6/0x490 inet_recvmsg+0x280/0x290 sock_recvmsg+0xfc/0x120 ____sys_recvmsg+0x160/0x3d0 ___sys_recvmsg+0xf0/0x180 __sys_recvmsg+0xea/0x1a0 do_syscall_64+0x3f/0x90 entry_SYSCALL_64_after_hwframe+0x72/0xdc The logic in tcp_bpf_recvmsg_parser is as follows: msg_bytes_ready: copied = sk_msg_recvmsg(sk, psock, msg, len, flags); if (!copied) { wait data; goto msg_bytes_ready; } In this case, "copied" always is 0, the infinite loop occurs. According to the Linux system call man page, 0 should be returned in this case. Therefore, in tcp_bpf_recvmsg_parser(), if the length is 0, directly return. Also modify several other functions with the same problem. Fixes: 1f5be6b3b0 ("udp: Implement udp_bpf_recvmsg() for sockmap") Fixes: 9825d866ce ("af_unix: Implement unix_dgram_bpf_recvmsg()") Fixes: c5d2177a72 ("bpf, sockmap: Fix race in ingress receive verdict with redirect to self") Fixes: 604326b41a ("bpf, sockmap: convert to generic sk_msg interface") Signed-off-by: Liu Jian <liujian56@huawei.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: John Fastabend <john.fastabend@gmail.com> Cc: Jakub Sitnicki <jakub@cloudflare.com> Link: https://lore.kernel.org/bpf/20230303080946.1146638-1-liujian56@huawei.com		2023-03-03 17:25:15 +01:00
..
af_unix.c	Networking changes for 6.3.	2023-02-21 18:24:12 -08:00
diag.c	af_unix: Get user_ns from in_skb in unix_diag_get_exact().	2022-12-01 10:32:20 +01:00
garbage.c	io_uring/af_unix: defer registered files gc to io_uring release	2022-10-12 16:30:34 -06:00
Kconfig	af_unix: Add OOB support	2021-08-04 09:55:52 +01:00
Makefile	af_unix: Implement ->psock_update_sk_prot()	2021-07-15 18:17:50 -07:00
scm.c	af_unix: annote lockless accesses to unix_tot_inflight & gc_in_progress	2022-01-14 18:31:37 -08:00
scm.h	net: split out functions related to registering inflight socket files	2019-02-28 08:24:23 -07:00
sysctl_net_unix.c	af_unix: fix unix_sysctl_register() error path	2022-07-09 12:27:33 +01:00
unix_bpf.c	bpf, sockmap: Fix an infinite loop error when len is 0 in tcp_bpf_recvmsg_parser()	2023-03-03 17:25:15 +01:00