From 41fb96a4b619afd2272acb6e981a7581efa8e118 Mon Sep 17 00:00:00 2001 From: Pankaj Dubey Date: Wed, 24 Sep 2014 16:25:54 +0530 Subject: [PATCH] kobject: fix NULL pointer derefernce in kobj_child_ns_ops We will hit NULL pointer dereference if we call platform_device_register_simple or platform_device_add at very early stage. I have observed following crash when called platform_device_add from "init_irq" hook of machine_desc. This patch fixes this issue and let system handle this case gracefully instead of kernel panic. [0.000000] Unable to handle kernel NULL pointer dereference at virtual address 0000000c [0.000000] pgd = c0004000 [0.000000] [0000000c] *pgd=00000000 [0.000000] Internal error: Oops: 5 [#1] PREEMPT ARM [0.000000] Modules linked in: [0.000000] CPU: 0 PID: 0 Comm: swapper Tainted: G W 3.17.0-rc6-00198-ga1603f1-dirty #319 [0.000000] task: c05b23f0 ti: c05a8000 task.ti: c05a8000 [0.000000] PC is at kobject_namespace+0x18/0x58 [0.000000] LR is at kobject_add_internal+0x90/0x2ec [snip] [0.000000] [] (kobject_namespace) from [] (kobject_add_internal+0x90/0x2ec) [0.000000] [] (kobject_add_internal) from [] (kobject_add+0x4c/0x98) [0.000000] [] (kobject_add) from [] (device_add+0xe8/0x51c) [0.000000] [] (device_add) from [] (platform_device_add+0xb4/0x214) [0.000000] [] (platform_device_add) from [] (platform_device_register_full+0xb8/0xdc) [0.000000] [] (platform_device_register_full) from [] (exynos_init_irq+0x90/0x9c) [0.000000] [] (exynos_init_irq) from [] (init_IRQ+0x2c/0x78) [0.000000] [] (init_IRQ) from [] (start_kernel+0x22c/0x378) [0.000000] [] (start_kernel) from [<40008070>] (0x40008070) [0.000000] Code: e590000c e3500000 0a00000e e5903014 (e593300c) Signed-off-by: Pankaj Dubey Signed-off-by: Greg Kroah-Hartman --- lib/kobject.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/lib/kobject.c b/lib/kobject.c index 58751bb80a7c..03d4ab349fa7 100644 --- a/lib/kobject.c +++ b/lib/kobject.c @@ -976,7 +976,7 @@ const struct kobj_ns_type_operations *kobj_child_ns_ops(struct kobject *parent) { const struct kobj_ns_type_operations *ops = NULL; - if (parent && parent->ktype->child_ns_type) + if (parent && parent->ktype && parent->ktype->child_ns_type) ops = parent->ktype->child_ns_type(parent); return ops; -- GitLab