Re: [PATCH] hyperv: a potential NULL pointer dereference

[Mukesh Ojha]

On 3/14/2019 11:16 AM, Kangjie Lu wrote:

In case alloc_page, the fix returns -ENOMEM to avoid the potential
NULL pointer dereference.

Signed-off-by: Kangjie Lu <k...@umn.edu>
---
  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);

Looks good to me.
Reviewed-by: Mukesh Ojha <mo...@codeaurora.org>


Thanks.
Mukesh