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

From: Mukesh Ojha
Date: Wed Mar 20 2019 - 11:50:31 EST



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 <kjlu@xxxxxxx>
---
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 <mojha@xxxxxxxxxxxxxx>


Thanks.
Mukesh