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

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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: 51ab30eb2ad4 ("x86/sgx: Replace section->init_laundry_list with sgx_dirty_page_list")
Reported-by: Paul Menzel <pmenzel@molgen.mpg.de>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Reinette 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
This commit is contained in:
Jarkko Sakkinen 2022-09-06 03:02:20 +03:00 committed by Dave Hansen
parent 5515d21c68
commit 133e049a3f
1 changed files with 9 additions and 6 deletions
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15
arch/x86/kernel/cpu/sgx/main.c
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@ -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())