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    SubjectRe: [PATCH -tip] x86: uv - prevent NULL dereference in uv_system_init
    On Sat, May 02, 2009 at 12:25:11AM +0400, Cyrill Gorcunov wrote:
    > [Cyrill Gorcunov - Sat, May 02, 2009 at 12:09:37AM +0400]
    > | [Ingo Molnar - Fri, May 01, 2009 at 10:03:31PM +0200]
    > | |
    > | | * Cyrill Gorcunov <gorcunov@openvz.org> wrote:
    > | |
    > | | > We may reach NULL dereference oops if kmalloc failed.
    > | | > Lets do panic better with sensible message.
    > | | >
    > | | > Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.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;
    > | |
    > | | hm, i think a BUG_ON() might be shorter and more appropriate here.
    > | | We really shouldnt be running out of memory during system init.
    > | |
    > | | Ingo
    > | |
    > |
    > | Yeah, indeed! I was thinking of __GPF_NOFAIL here as well with
    > | message on top like pr_debug("UV: allocating memory\n") or something
    > | like that. It would make it even cleaner I guess. Hmm?
    > |
    > | -- Cyrill
    >
    > Here is an updated one.


    Acked-by: Jack Steiner <steiner@sgi.com>


    >
    > -- Cyrill
    > ---
    > From: Cyrill Gorcunov <gorcunov@openvz.org>
    > Subject: [PATCH -tip] x86: uv - prevent NULL dereference in uv_system_init
    >
    > We may reach NULL dereference oops if kmalloc failed.
    > Prevent it with explisit BUG_ON.
    >
    > Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
    > ---
    > arch/x86/kernel/apic/x2apic_uv_x.c | 3 +++
    > 1 file changed, 3 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 +584,18 @@ void __init uv_system_init(void)
    >
    > bytes = sizeof(struct uv_blade_info) * uv_num_possible_blades();
    > uv_blade_info = kmalloc(bytes, GFP_KERNEL);
    > + BUG_ON(!uv_blade_info);
    >
    > 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);
    > + BUG_ON(!uv_node_to_blade);
    > 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);
    > + BUG_ON(!uv_cpu_to_blade);
    > memset(uv_cpu_to_blade, 255, bytes);
    >
    > blade = 0;


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