linux-kernel - [PATCH -tip] x86: uv - prevent NULL dereference in uv_system

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Date:	Fri, 1 May 2009 23:56:38 +0400
From:	Cyrill Gorcunov <gorcunov@...nvz.org>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	LKML <linux-kernel@...r.kernel.org>,
	Jack Steiner <steiner@....com>
Subject: [PATCH -tip] x86: uv - prevent NULL dereference in uv_system_init

We may reach NULL dereference oops if kmalloc failed.
Lets do panic better with sensible message.

Signed-off-by: Cyrill Gorcunov <gorcunov@...nvz.org>
---

Actually there is a dubious place as well at early_get_nodeid.
Is there a guarantee that we _never_ fail in early_ioremap?

 arch/x86/kernel/apic/x2apic_uv_x.c |    9 +++++++++
 1 file changed, 9 insertions(+)

Index: linux-2.6.git/arch/x86/kernel/apic/x2apic_uv_x.c
=====================================================================
--- linux-2.6.git.orig/arch/x86/kernel/apic/x2apic_uv_x.c
+++ linux-2.6.git/arch/x86/kernel/apic/x2apic_uv_x.c
@@ -584,15 +584,21 @@ void __init uv_system_init(void)
 
 	bytes = sizeof(struct uv_blade_info) * uv_num_possible_blades();
 	uv_blade_info = kmalloc(bytes, GFP_KERNEL);
+	if (!uv_blade_info)
+		goto err_nomem;
 
 	get_lowmem_redirect(&lowmem_redir_base, &lowmem_redir_size);
 
 	bytes = sizeof(uv_node_to_blade[0]) * num_possible_nodes();
 	uv_node_to_blade = kmalloc(bytes, GFP_KERNEL);
+	if (!uv_node_to_blade)
+		goto err_nomem;
 	memset(uv_node_to_blade, 255, bytes);
 
 	bytes = sizeof(uv_cpu_to_blade[0]) * num_possible_cpus();
 	uv_cpu_to_blade = kmalloc(bytes, GFP_KERNEL);
+	if (!uv_cpu_to_blade)
+		goto err_nomem;
 	memset(uv_cpu_to_blade, 255, bytes);
 
 	blade = 0;
@@ -667,4 +673,7 @@ void __init uv_system_init(void)
 	uv_cpu_init();
 	uv_scir_register_cpu_notifier();
 	proc_mkdir("sgi_uv", NULL);
+
+err_nomem:
+	panic("UV: Out of memory\n");
 }
--
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