From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from air.basealt.ru (air.basealt.ru [193.43.8.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4F29F19CD1D; Tue, 21 Apr 2026 13:28:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.43.8.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776778124; cv=none; b=h7mI1JqdVccKNETkt5DNs7fEDyMeJEjVaqs795uwC8oIlQNqk+EPSvC9aQrdpJeomGYzNaM94RcVCd5/2QuZV9qAdGNx5KJwH1Y10yj5GN+R0WIPzh8svP/cTVt00lptSVTTZ6mPscDcli1SLKcU2lbzyv2FcgeqTcO5mah2c2Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776778124; c=relaxed/simple; bh=CiIjqDjOBSPjKpkKMpR2vhnowJiMDTX30GTHEgLni5A=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=cv+ELtDAKyTcNcTUc+IMfuXs+jRVDUEeJ2Slra6TbUGTu3E9pScCXPXfEsF3A2XMTdkUzJWDzboTaMOdsAhq0R9V9+LpsYShU8x+i9Q/nQdkzo5IXgT4zaqiE4mvYM9G1rQ8X0AuDinqryN7VNES2++d6w4hJLzDToKlU8Ly1EM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=altlinux.org; spf=pass smtp.mailfrom=altlinux.org; arc=none smtp.client-ip=193.43.8.18 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=altlinux.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=altlinux.org Received: from altlinux.ipa.basealt.ru (unknown [193.43.11.2]) (Authenticated sender: kovalevvv) by air.basealt.ru (Postfix) with ESMTPSA id 9A5F723394; Tue, 21 Apr 2026 16:28:40 +0300 (MSK) From: Vasiliy Kovalev To: stable@vger.kernel.org Cc: Daniel Borkmann , Liu Jian , Jakub Sitnicki , bpf@vger.kernel.org, lvc-project@linuxtesting.org, kovalev@altlinux.org Subject: [PATCH 5.10.y] bpf, sockmap: Fix an infinite loop error when len is 0 in tcp_bpf_recvmsg_parser() Date: Tue, 21 Apr 2026 16:28:39 +0300 Message-Id: <20260421132839.38703-1-kovalev@altlinux.org> X-Mailer: git-send-email 2.33.8 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Liu Jian commit d900f3d20cc3169ce42ec72acc850e662a4d4db2 upstream. 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: 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: 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 Signed-off-by: Daniel Borkmann Acked-by: John Fastabend Cc: Jakub Sitnicki Link: https://lore.kernel.org/bpf/20230303080946.1146638-1-liujian56@huawei.com [ kovalev: bp to fix CVE-2023-53133; applied only to tcp_bpf_recvmsg as the older kernel lacks tcp_bpf_recvmsg_parser, udp_bpf_recvmsg and unix_bpf_recvmsg (see upstream commits c5d2177a72a1, 1f5be6b3b063 and 9825d866ce0d) ] Signed-off-by: Vasiliy Kovalev --- net/ipv4/tcp_bpf.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c index bcd5fc484f77..76cd97488777 100644 --- a/net/ipv4/tcp_bpf.c +++ b/net/ipv4/tcp_bpf.c @@ -277,6 +277,9 @@ 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, nonblock, flags, addr_len); -- 2.50.1