Commit 133e049a authored by Jarkko Sakkinen's avatar Jarkko Sakkinen Committed by Dave Hansen
Browse files

x86/sgx: Do not fail on incomplete sanitization on premature stop of ksgxd 



Unsanitized pages trigger WARN_ON() unconditionally, which can panic the
whole computer, if /proc/sys/kernel/panic_on_warn is set.

In sgx_init(), if misc_register() fails or misc_register() succeeds but
neither sgx_drv_init() nor sgx_vepc_init() succeeds, then ksgxd will be
prematurely stopped. This may leave unsanitized pages, which will result a
false warning.

Refine __sgx_sanitize_pages() to return:

1. Zero when the sanitization process is complete or ksgxd has been
   requested to stop.
2. The number of unsanitized pages otherwise.

Fixes: 51ab30eb ("x86/sgx: Replace section->init_laundry_list with sgx_dirty_page_list")
Reported-by: default avatarPaul Menzel <pmenzel@molgen.mpg.de>
Signed-off-by: default avatarJarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: default avatarDave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: default avatarReinette Chatre <reinette.chatre@intel.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/linux-sgx/20220825051827.246698-1-jarkko@kernel.org/T/#u
Link: https://lkml.kernel.org/r/20220906000221.34286-2-jarkko@kernel.org
parent 5515d21c

arch/x86/kernel/cpu/sgx/main.c

+9 −6
Original line number Diff line number Diff line
@@ -49,9 +49,13 @@ static LIST_HEAD(sgx_dirty_page_list); 
 * Reset post-kexec EPC pages to the uninitialized state. The pages are removed

 * from the input list, and made available for the page allocator. SECS pages

 * prepending their children in the input list are left intact.

 *

 * Return 0 when sanitization was successful or kthread was stopped, and the

 * number of unsanitized pages otherwise.

 */

static void __sgx_sanitize_pages(struct list_head *dirty_page_list)

static unsigned long __sgx_sanitize_pages(struct list_head *dirty_page_list)

{

	unsigned long left_dirty = 0;

	struct sgx_epc_page *page;

	LIST_HEAD(dirty);

	int ret;
@@ -59,7 +63,7 @@ static void __sgx_sanitize_pages(struct list_head *dirty_page_list) 
	/* dirty_page_list is thread-local, no need for a lock: */

	while (!list_empty(dirty_page_list)) {

		if (kthread_should_stop())

			return;

			return 0;



		page = list_first_entry(dirty_page_list, struct sgx_epc_page, list);
@@ -92,12 +96,14 @@ static void __sgx_sanitize_pages(struct list_head *dirty_page_list) 
		} else {

			/* The page is not yet clean - move to the dirty list. */

			list_move_tail(&page->list, &dirty);

			left_dirty++;

		}



		cond_resched();

	}



	list_splice(&dirty, dirty_page_list);

	return left_dirty;

}



static bool sgx_reclaimer_age(struct sgx_epc_page *epc_page)
@@ -395,10 +401,7 @@ static int ksgxd(void *p) 
	 * required for SECS pages, whose child pages blocked EREMOVE.

	 */

	__sgx_sanitize_pages(&sgx_dirty_page_list);

	__sgx_sanitize_pages(&sgx_dirty_page_list);



	/* sanity check: */

	WARN_ON(!list_empty(&sgx_dirty_page_list));

	WARN_ON(__sgx_sanitize_pages(&sgx_dirty_page_list));



	while (!kthread_should_stop()) {

		if (try_to_freeze())