On Wed, Mar 03, 2021 at 08:56:52AM -0800, Dave Hansen wrote:
> On 3/3/21 7:03 AM, Jarkko Sakkinen wrote:
> > If sgx_page_cache_init() fails in the middle, a trivial return
> > statement causes unused memory and virtual address space reserved for
> > the EPC section, not freed. Fix this by using the same rollback, as
> > when sgx_page_reclaimer_init() fails.
> ...
> > @@ -708,8 +708,10 @@ static int __init sgx_init(void)
> > if (!cpu_feature_enabled(X86_FEATURE_SGX))
> > return -ENODEV;
> >
> > - if (!sgx_page_cache_init())
> > - return -ENOMEM;
> > + if (!sgx_page_cache_init()) {
> > + ret = -ENOMEM;
> > + goto err_page_cache;
> > + }
>
>
> Currently, the only way sgx_page_cache_init() can fail is in the case
> that there are no sections:
>
> if (!sgx_nr_epc_sections) {
> pr_err("There are zero EPC sections.\n");
> return false;
> }
>
> That only happened if all sgx_setup_epc_section() calls failed.
> sgx_setup_epc_section() never both allocates memory with vmalloc for
> section->pages *and* fails. If sgx_setup_epc_section() has a successful
> memremap() but a failed vmalloc(), it cleans up with memunmap().
>
> In other words, I see how this _looks_ like a memory leak from
> sgx_init(), but I don't see an actual leak in practice.
>
> Am I missing something?
In sgx_setup_epc_section():
section->pages = vmalloc(nr_pages * sizeof(struct sgx_epc_page));
if (!section->pages) {
memunmap(section->virt_addr);
return false;
}
I.e. this rollback does not happen without this fix applied:
for (i = 0; i < sgx_nr_epc_sections; i++) {
vfree(sgx_epc_sections[i].pages);
memunmap(sgx_epc_sections[i].virt_addr);
}
/Jarkko
