diff mbox series

[bpf,v2] bpf, sockmap: fix an infinite loop error when len is 0 in tcp_bpf_recvmsg_parser()

Message ID 20230303080946.1146638-1-liujian56@huawei.com (mailing list archive)
State Accepted
Delegated to: BPF
Headers show
Series [bpf,v2] bpf, sockmap: fix an infinite loop error when len is 0 in tcp_bpf_recvmsg_parser() | expand

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bpf/vmtest-bpf-PR success PR summary
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netdev/series_format success Single patches do not need cover letters
netdev/tree_selection success Clearly marked for bpf
netdev/fixes_present success Fixes tag present in non-next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 2 this patch: 2
netdev/cc_maintainers success CCed 12 of 12 maintainers
netdev/build_clang success Errors and warnings before: 0 this patch: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
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netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 36 lines checked
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Commit Message

Liu Jian March 3, 2023, 8:09 a.m. UTC 
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" alway 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: 1f5be6b3b063 ("udp: Implement udp_bpf_recvmsg() for sockmap")
Fixes: 9825d866ce0d ("af_unix: Implement unix_dgram_bpf_recvmsg()")
Fixes: c5d2177a72a1 ("bpf, sockmap: Fix race in ingress receive verdict with redirect to self")
Fixes: 604326b41a6f ("bpf, sockmap: convert to generic sk_msg interface")
Signed-off-by: Liu Jian <liujian56@huawei.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
---
v1->v2: change "if (len == 0)" to "if (!len)"
 net/ipv4/tcp_bpf.c  | 6 ++++++
 net/ipv4/udp_bpf.c  | 3 +++
 net/unix/unix_bpf.c | 3 +++
 3 files changed, 12 insertions(+)
diff mbox series

Patch

diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c
index cf26d65ca389..ebf917511937 100644
--- a/net/ipv4/tcp_bpf.c
+++ b/net/ipv4/tcp_bpf.c
@@ -186,6 +186,9 @@  static int tcp_bpf_recvmsg_parser(struct sock *sk,
 	if (unlikely(flags & MSG_ERRQUEUE))
 		return inet_recv_error(sk, msg, len, addr_len);
 
+	if (!len)
+		return 0;
+
 	psock = sk_psock_get(sk);
 	if (unlikely(!psock))
 		return tcp_recvmsg(sk, msg, len, flags, addr_len);
@@ -244,6 +247,9 @@  static int tcp_bpf_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
 	if (unlikely(flags & MSG_ERRQUEUE))
 		return inet_recv_error(sk, msg, len, addr_len);
 
+	if (!len)
+		return 0;
+
 	psock = sk_psock_get(sk);
 	if (unlikely(!psock))
 		return tcp_recvmsg(sk, msg, len, flags, addr_len);
diff --git a/net/ipv4/udp_bpf.c b/net/ipv4/udp_bpf.c
index e5dc91d0e079..0735d820e413 100644
--- a/net/ipv4/udp_bpf.c
+++ b/net/ipv4/udp_bpf.c
@@ -68,6 +68,9 @@  static int udp_bpf_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
 	if (unlikely(flags & MSG_ERRQUEUE))
 		return inet_recv_error(sk, msg, len, addr_len);
 
+	if (!len)
+		return 0;
+
 	psock = sk_psock_get(sk);
 	if (unlikely(!psock))
 		return sk_udp_recvmsg(sk, msg, len, flags, addr_len);
diff --git a/net/unix/unix_bpf.c b/net/unix/unix_bpf.c
index e9bf15513961..2f9d8271c6ec 100644
--- a/net/unix/unix_bpf.c
+++ b/net/unix/unix_bpf.c
@@ -54,6 +54,9 @@  static int unix_bpf_recvmsg(struct sock *sk, struct msghdr *msg,
 	struct sk_psock *psock;
 	int copied;
 
+	if (!len)
+		return 0;
+
 	psock = sk_psock_get(sk);
 	if (unlikely(!psock))
 		return __unix_recvmsg(sk, msg, len, flags);