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SubjectRE: [PATCH] hyperv: a potential NULL pointer dereference
Date


> -----Original Message-----
> From: Kangjie Lu <kjlu@umn.edu>
> Sent: Wednesday, March 13, 2019 10:47 PM
> To: kjlu@umn.edu
> Cc: pakki001@umn.edu; KY Srinivasan <kys@microsoft.com>; Haiyang Zhang
> <haiyangz@microsoft.com>; Stephen Hemminger
> <sthemmin@microsoft.com>; Sasha Levin <sashal@kernel.org>; Thomas
> Gleixner <tglx@linutronix.de>; Ingo Molnar <mingo@redhat.com>; Borislav
> Petkov <bp@alien8.de>; H. Peter Anvin <hpa@zytor.com>; x86@kernel.org;
> linux-hyperv@vger.kernel.org; linux-kernel@vger.kernel.org
> Subject: [PATCH] hyperv: a potential NULL pointer dereference
>
> In case alloc_page, the fix returns -ENOMEM to avoid the potential
> NULL pointer dereference.
>
Thanks.

> Signed-off-by: Kangjie Lu <kjlu@umn.edu>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>

> ---
> arch/x86/hyperv/hv_init.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
> index 7abb09e2eeb8..dfdb4ce1ae9c 100644
> --- a/arch/x86/hyperv/hv_init.c
> +++ b/arch/x86/hyperv/hv_init.c
> @@ -102,9 +102,13 @@ static int hv_cpu_init(unsigned int cpu)
> u64 msr_vp_index;
> struct hv_vp_assist_page **hvp =
> &hv_vp_assist_page[smp_processor_id()];
> void **input_arg;
> + struct page *pg;
>
> input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
> - *input_arg = page_address(alloc_page(GFP_KERNEL));
> + pg = alloc_page(GFP_KERNEL);
> + if (unlikely(!pg))
> + return -ENOMEM;
> + *input_arg = page_address(pg);
>
> hv_get_vp_index(msr_vp_index);
>
> --
> 2.17.1

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