blob: c18a84a1311c0cf8dcee783c6b75ad197d90c6b0 [file] [log] [blame]
From 62f8f9d4ce895e3cc82e572c9b7e76db800f9380 Mon Sep 17 00:00:00 2001
From: Vasily Gorbik <>
Date: Thu, 19 Sep 2019 15:55:17 +0200
Subject: [PATCH] s390/cio: exclude subchannels with no parent from pseudo
commit ab5758848039de9a4b249d46e4ab591197eebaf2 upstream.
ccw console is created early in start_kernel and used before css is
initialized or ccw console subchannel is registered. Until then console
subchannel does not have a parent. For that reason assume subchannels
with no parent are not pseudo subchannels. This fixes the following
kasan finding:
BUG: KASAN: global-out-of-bounds in sch_is_pseudo_sch+0x8e/0x98
Read of size 8 at addr 00000000000005e8 by task swapper/0/0
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.3.0-rc8-07370-g6ac43dd12538 #2
Hardware name: IBM 2964 NC9 702 (z/VM 6.4.0)
Call Trace:
([<000000000012cd76>] show_stack+0x14e/0x1e0)
[<0000000001f7fb44>] dump_stack+0x1a4/0x1f8
[<00000000007d7afc>] print_address_description+0x64/0x3c8
[<00000000007d75f6>] __kasan_report+0x14e/0x180
[<00000000018a2986>] sch_is_pseudo_sch+0x8e/0x98
[<000000000189b950>] cio_enable_subchannel+0x1d0/0x510
[<00000000018cac7c>] ccw_device_recognition+0x12c/0x188
[<0000000002ceb1a8>] ccw_device_enable_console+0x138/0x340
[<0000000002cf1cbe>] con3215_init+0x25e/0x300
[<0000000002c8770a>] console_init+0x68a/0x9b8
[<0000000002c6a3d6>] start_kernel+0x4fe/0x728
[<0000000000100070>] startup_continue+0x70/0xd0
Reviewed-by: Sebastian Ott <>
Signed-off-by: Vasily Gorbik <>
Signed-off-by: Paul Gortmaker <>
diff --git a/drivers/s390/cio/css.c b/drivers/s390/cio/css.c
index aea502922646..df09ed53ab45 100644
--- a/drivers/s390/cio/css.c
+++ b/drivers/s390/cio/css.c
@@ -1213,6 +1213,8 @@ device_initcall(cio_settle_init);
int sch_is_pseudo_sch(struct subchannel *sch)
+ if (!sch->dev.parent)
+ return 0;
return sch == to_css(sch->dev.parent)->pseudo_subchannel;