Messages in this thread | | | Subject | Re: [PATCH v3 1/7] x86/sgx: Provide indication of life-cycle of EPC pages | From | Dave Hansen <> | Date | Wed, 28 Jul 2021 15:12:03 -0700 |
| |
On 7/28/21 1:46 PM, Tony Luck wrote: > +++ b/arch/x86/kernel/cpu/sgx/main.c > @@ -581,7 +581,7 @@ struct sgx_epc_page *sgx_alloc_epc_page(void *owner, bool reclaim) > for ( ; ; ) { > page = __sgx_alloc_epc_page(); > if (!IS_ERR(page)) { > - page->owner = owner; > + page->owner = owner ? owner : page; > break; > }
I'm a little worried about this.
Let's say we get confused about the type of the page and dereference page->owner. If it's NULL, we get a nice oops. If it's a real, valid pointer, we get real valid memory back that we can scribble on.
Wouldn't it be safer to do something like:
page->owner = owner ? owner : (void *)-1;
-1 is non-NULL, but also invalid, which makes it harder for us to poke ourselves in the eye.
| |