[PATCH AUTOSEL 5.13 180/219] of: Don't allow __of_attached_node_sysfs() without CONFIG_SYSFS

Sasha Levin
2021-09-09T12:30:59Z

From: Marc Zyngier <maz@kernel.org>

[ Upstream commit 6211e9cb2f8faf7faae0b6caf844bfe9527cc607 ]

Trying to boot without SYSFS, but with OF_DYNAMIC quickly
results in a crash:

[ 0.088460] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000070
[...]
[ 0.103927] CPU: 1 PID: 1 Comm: swapper/0 Not tainted 5.14.0-rc3 #4179
[ 0.105810] Hardware name: linux,dummy-virt (DT)
[ 0.107147] pstate: 80000005 (Nzcv daif -PAN -UAO -TCO BTYPE=--)
[ 0.108876] pc : kernfs_find_and_get_ns+0x3c/0x7c
[ 0.110244] lr : kernfs_find_and_get_ns+0x3c/0x7c
[...]
[ 0.134087] Call trace:
[ 0.134800] kernfs_find_and_get_ns+0x3c/0x7c
[ 0.136054] safe_name+0x4c/0xd0
[ 0.136994] __of_attach_node_sysfs+0xf8/0x124
[ 0.138287] of_core_init+0x90/0xfc
[ 0.139296] driver_init+0x30/0x4c
[ 0.140283] kernel_init_freeable+0x160/0x1b8
[ 0.141543] kernel_init+0x30/0x140
[ 0.142561] ret_from_fork+0x10/0x18

While not having sysfs isn't a very common option these days,
it is still expected that such configuration would work.

Paper over it by bailing out from __of_attach_node_sysfs() if
CONFIG_SYSFS isn't enabled.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210820144722.169226-1-maz@kernel.org
Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/of/kobj.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/of/kobj.c b/drivers/of/kobj.c
index a32e60b024b8..6675b5e56960 100644
--- a/drivers/of/kobj.c
+++ b/drivers/of/kobj.c
@@ -119,7 +119,7 @@ int __of_attach_node_sysfs(struct device_node *np)
struct property *pp;
int rc;

- if (!of_kset)
+ if (!IS_ENABLED(CONFIG_SYSFS) || !of_kset)
return 0;

np->kobj.kset = of_kset;
--
2.30.2