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    Subject[PATCH AUTOSEL 4.19 58/74] of: Don't allow __of_attached_node_sysfs() without CONFIG_SYSFS
    Date
    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
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