ipack: ipoctal: fix missing allocation-failure check

stable inclusion
from stable-5.10.71
commit 843efca98e6a24a917585247883d7cc34e9fe077
bugzilla: 182981 https://gitee.com/openeuler/kernel/issues/I4I3KD

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=843efca98e6a24a917585247883d7cc34e9fe077

--------------------------------

commit 445c8132 upstream.

Add the missing error handling when allocating the transmit buffer to
avoid dereferencing a NULL pointer in write() should the allocation
ever fail.

Fixes: ba4dc61f ("Staging: ipack: add support for IP-OCTAL mezzanine board")
Cc: stable@vger.kernel.org      # 3.5
Acked-by: NSamuel Iglesias Gonsalvez <siglesias@igalia.com>
Signed-off-by: NJohan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210917114622.5412-5-johan@kernel.orgSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Acked-by: NWeilong Chen <chenweilong@huawei.com>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

drivers/ipack/devices/ipoctal.c

@@ -388,7 +388,9 @@ static int ipoctal_inst_slot(struct ipoctal *ipoctal, unsigned int bus_nr,
 
 		channel = &ipoctal->channel[i];
 		tty_port_init(&channel->tty_port);
-		tty_port_alloc_xmit_buf(&channel->tty_port);
+		res = tty_port_alloc_xmit_buf(&channel->tty_port);
+		if (res)
+			continue;
 		channel->tty_port.ops = &ipoctal_tty_port_ops;
 
 		ipoctal_reset_stats(&channel->stats);