netdev - [PATCH net v2] tun: Check tun device queue status in tun_chr_write

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Message-ID: <20220915123539.35956-1-liujian56@huawei.com>
Date:   Thu, 15 Sep 2022 20:35:39 +0800
From:   Liu Jian <liujian56@...wei.com>
To:     <davem@...emloft.net>, <edumazet@...gle.com>, <kuba@...nel.org>,
        <pabeni@...hat.com>, <ast@...nel.org>, <daniel@...earbox.net>,
        <hawk@...nel.org>, <john.fastabend@...il.com>,
        <jasowang@...hat.com>, <netdev@...r.kernel.org>
CC:     <liujian56@...wei.com>
Subject: [PATCH net v2] tun: Check tun device queue status in tun_chr_write_iter

syzbot found below warning:

------------[ cut here ]------------
geneve0 received packet on queue 3, but number of RX queues is 3
WARNING: CPU: 1 PID: 29734 at net/core/dev.c:4611 netif_get_rxqueue net/core/dev.c:4611 [inline]
WARNING: CPU: 1 PID: 29734 at net/core/dev.c:4611 netif_receive_generic_xdp+0xb10/0xb50 net/core/dev.c:4683
Modules linked in:
CPU: 1 PID: 29734 Comm: syz-executor.0 Not tainted 5.10.0 #5
Hardware name: linux,dummy-virt (DT)
pstate: 60400005 (nZCv daif +PAN -UAO -TCO BTYPE=--)
pc : netif_get_rxqueue net/core/dev.c:4611 [inline]
pc : netif_receive_generic_xdp+0xb10/0xb50 net/core/dev.c:4683
lr : netif_get_rxqueue net/core/dev.c:4611 [inline]
lr : netif_receive_generic_xdp+0xb10/0xb50 net/core/dev.c:4683
sp : ffffa00016127770
x29: ffffa00016127770 x28: ffff3f4607d6acb4
x27: ffff3f4607d6acb0 x26: ffff3f4607d6ad20
x25: ffff3f461de3c000 x24: ffff3f4607d6ad28
x23: ffffa00010059000 x22: ffff3f4608719100
x21: 0000000000000003 x20: ffffa000161278a0
x19: ffff3f4607d6ac40 x18: 0000000000000000
x17: 0000000000000000 x16: 00000000f2f2f204
x15: 00000000f2f20000 x14: 6465766965636572
x13: 20306576656e6567 x12: ffff98b8ed3b924d
x11: 1ffff8b8ed3b924c x10: ffff98b8ed3b924c
x9 : ffffc5c76525c9c4 x8 : 0000000000000000
x7 : 0000000000000001 x6 : ffff98b8ed3b924c
x5 : ffff3f460f3b29c0 x4 : dfffa00000000000
x3 : ffffc5c765000000 x2 : 0000000000000000
x1 : 0000000000000000 x0 : ffff3f460f3b29c0
Call trace:
 netif_get_rxqueue net/core/dev.c:4611 [inline]
 netif_receive_generic_xdp+0xb10/0xb50 net/core/dev.c:4683
 do_xdp_generic net/core/dev.c:4777 [inline]
 do_xdp_generic+0x9c/0x190 net/core/dev.c:4770
 tun_get_user+0xd94/0x2010 drivers/net/tun.c:1938
 tun_chr_write_iter+0x98/0x100 drivers/net/tun.c:2036
 call_write_iter include/linux/fs.h:1960 [inline]
 new_sync_write+0x260/0x370 fs/read_write.c:515
 vfs_write+0x51c/0x61c fs/read_write.c:602
 ksys_write+0xfc/0x200 fs/read_write.c:655
 __do_sys_write fs/read_write.c:667 [inline]
 __se_sys_write fs/read_write.c:664 [inline]
 __arm64_sys_write+0x50/0x60 fs/read_write.c:664
 __invoke_syscall arch/arm64/kernel/syscall.c:36 [inline]
 invoke_syscall arch/arm64/kernel/syscall.c:48 [inline]
 el0_svc_common.constprop.0+0xf4/0x414 arch/arm64/kernel/syscall.c:155
 do_el0_svc+0x50/0x11c arch/arm64/kernel/syscall.c:217
 el0_svc+0x20/0x30 arch/arm64/kernel/entry-common.c:353
 el0_sync_handler+0xe4/0x1e0 arch/arm64/kernel/entry-common.c:369
 el0_sync+0x148/0x180 arch/arm64/kernel/entry.S:683

This is because the detached queue is used to send data. Therefore, we need
to check the queue status in the tun_chr_write_iter function.

Fixes: cde8b15f1aab ("tuntap: add ioctl to attach or detach a file form tuntap device")
Signed-off-by: Liu Jian <liujian56@...wei.com>
---
v1->v2: add fixes tag
 drivers/net/tun.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 259b2b84b2b3..261411c1a6bb 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -2019,6 +2019,11 @@ static ssize_t tun_chr_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	if (!tun)
 		return -EBADFD;
 
+	if (tfile->detached) {
+		tun_put(tun);
+		return -ENETDOWN;
+	}
+
 	if ((file->f_flags & O_NONBLOCK) || (iocb->ki_flags & IOCB_NOWAIT))
 		noblock = 1;
 
-- 
2.17.1