Messages in this thread Patch in this message | | | Subject | Re: [PATCH] bpf/sockmap: fix kernel panic at __tcp_bpf_recvmsg | From | dihu <> | Date | Fri, 29 May 2020 17:05:12 +0800 |
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On 2020/5/27 5:10, John Fastabend wrote: > dihu wrote: >> From 865a45747de6b68fd02a0ff128a69a5c8feb73c3 Mon Sep 17 00:00:00 2001 >> From: dihu <anny.hu@linux.alibaba.com> >> Date: Mon, 25 May 2020 17:23:16 +0800 >> Subject: [PATCH] bpf/sockmap: fix kernel panic at __tcp_bpf_recvmsg >> >> 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..c0d4624 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; > > Thanks. Change looks good but spacing is a bit off . Can we > turn those spaces into tabs? Otherwise adding fixes tag and > my ack would be great. > > Fixes: 02c558b2d5d67 ("bpf: sockmap, support for msg_peek in sk_msg with redirect ingress") > Acked-by: John Fastabend <john.fastabend@gmail.com>
From 127a334fa5e5d029353ceb1a0414886c527f4be5 Mon Sep 17 00:00:00 2001 From: dihu <anny.hu@linux.alibaba.com> Date: Fri, 29 May 2020 16:38:50 +0800 Subject: [PATCH] bpf/sockmap: fix kernel panic at __tcp_bpf_recvmsg
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
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