[PATCH AUTOSEL 5.4 164/205] bpf: skmsg, fix potential psock NULL pointer dereference
From: Sasha Levin <sashal@kernel.org>
Date: 2020-01-16 16:54:06
Also in:
bpf, lkml, stable
Subsystem:
bpf [l7 framework] (sockmap), networking [general], the rest · Maintainers:
John Fastabend, Jakub Sitnicki, Jiayuan Chen, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
From: John Fastabend <john.fastabend@gmail.com>
[ Upstream commit 8163999db445021f2651a8a47b5632483e8722ea ]
Report from Dan Carpenter,
net/core/skmsg.c:792 sk_psock_write_space()
error: we previously assumed 'psock' could be null (see line 790)
net/core/skmsg.c
789 psock = sk_psock(sk);
790 if (likely(psock && sk_psock_test_state(psock, SK_PSOCK_TX_ENABLED)))
Check for NULL
791 schedule_work(&psock->work);
792 write_space = psock->saved_write_space;
^^^^^^^^^^^^^^^^^^^^^^^^
793 rcu_read_unlock();
794 write_space(sk);
Ensure psock dereference on line 792 only occurs if psock is not null.
Reported-by: Dan Carpenter <redacted>
Fixes: 604326b41a6f ("bpf, sockmap: convert to generic sk_msg interface")
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/core/skmsg.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)
diff --git a/net/core/skmsg.c b/net/core/skmsg.c
index 0675d022584e..ded2d5227678 100644
--- a/net/core/skmsg.c
+++ b/net/core/skmsg.c@@ -793,15 +793,18 @@ static void sk_psock_strp_data_ready(struct sock *sk) static void sk_psock_write_space(struct sock *sk) { struct sk_psock *psock; - void (*write_space)(struct sock *sk); + void (*write_space)(struct sock *sk) = NULL; rcu_read_lock(); psock = sk_psock(sk); - if (likely(psock && sk_psock_test_state(psock, SK_PSOCK_TX_ENABLED))) - schedule_work(&psock->work); - write_space = psock->saved_write_space; + if (likely(psock)) { + if (sk_psock_test_state(psock, SK_PSOCK_TX_ENABLED)) + schedule_work(&psock->work); + write_space = psock->saved_write_space; + } rcu_read_unlock(); - write_space(sk); + if (write_space) + write_space(sk); } int sk_psock_init_strp(struct sock *sk, struct sk_psock *psock)
--
2.20.1