From: dihu <anny.hu@linux.alibaba.com>
To: bpf@vger.kernel.org
Cc: netdev@vger.kernel.org, dihu <anny.hu@linux.alibaba.com>
Subject: [PATCH] bpf/sockmap: fix kernel panic at __tcp_bpf_recvmsg
Date: Fri, 5 Jun 2020 16:46:25 +0800 [thread overview]
Message-ID: <20200605084625.9783-1-anny.hu@linux.alibaba.com> (raw)
When user application calls read() with MSG_PEEK flag to read data
of bpf sockmap socket, kernel panic happens at
__tcp_bpf_recvmsg+0x12c/0x350. sk_msg is not removed from ingress_msg
queue after read out under MSG_PEEK flag is set. Because it's not
judged whether sk_msg is the last msg of ingress_msg queue, the next
sk_msg may be the head of ingress_msg queue, whose memory address of
sg page is invalid. So it's necessary to add check codes to prevent
this problem.
[20759.125457] BUG: kernel NULL pointer dereference, address:
0000000000000008
[20759.132118] CPU: 53 PID: 51378 Comm: envoy Tainted: G E
5.4.32 #1
[20759.140890] Hardware name: Inspur SA5212M4/YZMB-00370-109, BIOS
4.1.12 06/18/2017
[20759.149734] RIP: 0010:copy_page_to_iter+0xad/0x300
[20759.270877] __tcp_bpf_recvmsg+0x12c/0x350
[20759.276099] tcp_bpf_recvmsg+0x113/0x370
[20759.281137] inet_recvmsg+0x55/0xc0
[20759.285734] __sys_recvfrom+0xc8/0x130
[20759.290566] ? __audit_syscall_entry+0x103/0x130
[20759.296227] ? syscall_trace_enter+0x1d2/0x2d0
[20759.301700] ? __audit_syscall_exit+0x1e4/0x290
[20759.307235] __x64_sys_recvfrom+0x24/0x30
[20759.312226] do_syscall_64+0x55/0x1b0
[20759.316852] entry_SYSCALL_64_after_hwframe+0x44/0xa9
Signed-off-by: dihu <anny.hu@linux.alibaba.com>
---
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 5a05327..b82e4c3 100644
--- a/net/ipv4/tcp_bpf.c
+++ b/net/ipv4/tcp_bpf.c
@@ -64,6 +64,9 @@ int __tcp_bpf_recvmsg(struct sock *sk, struct sk_psock *psock,
} while (i != msg_rx->sg.end);
if (unlikely(peek)) {
+ if (msg_rx == list_last_entry(&psock->ingress_msg,
+ struct sk_msg, list))
+ break;
msg_rx = list_next_entry(msg_rx, list);
continue;
}
--
1.8.3.1
next reply other threads:[~2020-06-05 8:46 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-05 8:46 dihu [this message]
2020-06-08 16:06 ` [PATCH] bpf/sockmap: fix kernel panic at __tcp_bpf_recvmsg John Fastabend
2020-06-09 9:03 ` Jakub Sitnicki
2020-06-09 17:58 ` Alexei Starovoitov
[not found] <db5393a3-d4b3-45c1-8219-f23b43a8d2ab.anny.hu@linux.alibaba.com>
2020-05-26 21:10 ` John Fastabend
2020-05-29 9:05 ` dihu
2020-06-02 9:03 ` Jakub Sitnicki
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