From: Duoming Zhou <duoming@zju.edu.cn>
To: linux-hams@vger.kernel.org, pabeni@redhat.com
Cc: ralf@linux-mips.org, davem@davemloft.net, edumazet@google.com,
kuba@kernel.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org, Duoming Zhou <duoming@zju.edu.cn>
Subject: [PATCH net v3 2/2] net: rose: fix null-ptr-deref caused by rose_kill_by_neigh
Date: Fri, 24 Jun 2022 09:05:45 +0800 [thread overview]
Message-ID: <c31f454f74833b2003713fffa881aabb190b8290.1656031586.git.duoming@zju.edu.cn> (raw)
In-Reply-To: <cover.1656031586.git.duoming@zju.edu.cn>
In-Reply-To: <cover.1656031586.git.duoming@zju.edu.cn>
When the link layer connection is broken, the rose->neighbour is
set to null. But rose->neighbour could be used by rose_connection()
and rose_release() later, because there is no synchronization among
them. As a result, the null-ptr-deref bugs will happen.
One of the null-ptr-deref bugs is shown below:
(thread 1) | (thread 2)
| rose_connect
rose_kill_by_neigh | lock_sock(sk)
spin_lock_bh(&rose_list_lock) | if (!rose->neighbour)
rose->neighbour = NULL;//(1) |
| rose->neighbour->use++;//(2)
The rose->neighbour is set to null in position (1) and dereferenced
in position (2).
The KASAN report triggered by POC is shown below:
KASAN: null-ptr-deref in range [0x0000000000000028-0x000000000000002f]
...
RIP: 0010:rose_connect+0x6c2/0xf30
RSP: 0018:ffff88800ab47d60 EFLAGS: 00000206
RAX: 0000000000000005 RBX: 000000000000002a RCX: 0000000000000000
RDX: ffff88800ab38000 RSI: ffff88800ab47e48 RDI: ffff88800ab38309
RBP: dffffc0000000000 R08: 0000000000000000 R09: ffffed1001567062
R10: dfffe91001567063 R11: 1ffff11001567061 R12: 1ffff11000d17cd0
R13: ffff8880068be680 R14: 0000000000000002 R15: 1ffff11000d17cd0
...
Call Trace:
<TASK>
? __local_bh_enable_ip+0x54/0x80
? selinux_netlbl_socket_connect+0x26/0x30
? rose_bind+0x5b0/0x5b0
__sys_connect+0x216/0x280
__x64_sys_connect+0x71/0x80
do_syscall_64+0x43/0x90
entry_SYSCALL_64_after_hwframe+0x46/0xb0
This patch adds lock_sock() in rose_kill_by_neigh() in order to
synchronize with rose_connect() and rose_release().
Meanwhile, this patch adds sock_hold() protected by rose_list_lock
that could synchronize with rose_remove_socket() in order to mitigate
UAF bug caused by lock_sock() we add.
What's more, there is no need using rose_neigh_list_lock to protect
rose_kill_by_neigh(). Because we have already used rose_neigh_list_lock
to protect the state change of rose_neigh in rose_link_failed(), which
is well synchronized.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
---
Changes since v2:
- v2: Fix refcount leak of sock.
net/rose/af_rose.c | 6 ++++++
net/rose/rose_route.c | 2 ++
2 files changed, 8 insertions(+)
diff --git a/net/rose/af_rose.c b/net/rose/af_rose.c
index bf2d986a6bc..5caa222c490 100644
--- a/net/rose/af_rose.c
+++ b/net/rose/af_rose.c
@@ -169,9 +169,15 @@ void rose_kill_by_neigh(struct rose_neigh *neigh)
struct rose_sock *rose = rose_sk(s);
if (rose->neighbour == neigh) {
+ sock_hold(s);
rose_disconnect(s, ENETUNREACH, ROSE_OUT_OF_ORDER, 0);
rose->neighbour->use--;
+ spin_unlock_bh(&rose_list_lock);
+ lock_sock(s);
rose->neighbour = NULL;
+ release_sock(s);
+ spin_lock_bh(&rose_list_lock);
+ sock_put(s);
}
}
spin_unlock_bh(&rose_list_lock);
diff --git a/net/rose/rose_route.c b/net/rose/rose_route.c
index fee6409c2bb..b116828b422 100644
--- a/net/rose/rose_route.c
+++ b/net/rose/rose_route.c
@@ -827,7 +827,9 @@ void rose_link_failed(ax25_cb *ax25, int reason)
ax25_cb_put(ax25);
rose_del_route_by_neigh(rose_neigh);
+ spin_unlock_bh(&rose_neigh_list_lock);
rose_kill_by_neigh(rose_neigh);
+ return;
}
spin_unlock_bh(&rose_neigh_list_lock);
}
--
2.17.1
next prev parent reply other threads:[~2022-06-24 1:05 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-24 1:05 [PATCH net v3 0/2] Fix UAF and null-ptr-deref bugs in rose protocol Duoming Zhou
2022-06-24 1:05 ` [PATCH net v3 1/2] net: rose: fix UAF bugs caused by timer handler Duoming Zhou
2022-06-24 1:05 ` Duoming Zhou [this message]
2022-06-28 11:12 ` [PATCH net v3 2/2] net: rose: fix null-ptr-deref caused by rose_kill_by_neigh Paolo Abeni
2022-06-29 3:48 ` duoming
2022-06-29 12:54 ` Dan Cross
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