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.
Link: https://lore.kernel.org/linux-sgx/[email protected]/T/#u
Fixes: 51ab30eb2ad4 ("x86/sgx: Replace section->init_laundry_list with sgx_dirty_page_list")
Cc: [email protected] # v5.13+
Reported-by: Paul Menzel <[email protected]>
Signed-off-by: Jarkko Sakkinen <[email protected]>
---
v9:
- Remove left_dirty declaratio from ksgxd().
- Update commit message.
v8:
- Discard changes that are not relevant for the stable fix. This
does absolutely minimum to address the bug:
https://lore.kernel.org/linux-sgx/[email protected]/
v7:
- Rewrote commit message.
- Do not return -ECANCELED on premature stop. Instead use zero both
premature stop and complete sanitization.
v6:
- Address Reinette's feedback:
https://lore.kernel.org/linux-sgx/Yw6%2FiTzSdSw%2FY%[email protected]/
v5:
- Add the klog dump and sysctl option to the commit message.
v4:
- Explain expectations for dirty_page_list in the function header, instead
of an inline comment.
- Improve commit message to explain the conditions better.
- Return the number of pages left dirty to ksgxd() and print warning after
the 2nd call, if there are any.
v3:
- Remove WARN_ON().
- Tuned comments and the commit message a bit.
v2:
- Replaced WARN_ON() with optional pr_info() inside
__sgx_sanitize_pages().
- Rewrote the commit message.
- Added the fixes tag.
---
arch/x86/kernel/cpu/sgx/main.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)
diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index 515e2a5f25bb..0aad028f04d4 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -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())
--
2.37.2
On Tue, 2022-09-06 at 03:02 +0300, Jarkko Sakkinen wrote:
> 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.
>
> Link: https://lore.kernel.org/linux-sgx/[email protected]/T/#u
> Fixes: 51ab30eb2ad4 ("x86/sgx: Replace section->init_laundry_list with sgx_dirty_page_list")
> Cc: [email protected] # v5.13+
> Reported-by: Paul Menzel <[email protected]>
> Signed-off-by: Jarkko Sakkinen <[email protected]>
(Given the idea of moving sgx_page_reclaimer_init() to the end of sgx_init() is
considered too big to fix this bug:)
Acked-by: Kai Huang <[email protected]>
--
Thanks,
-Kai
On 9/5/2022 5:02 PM, Jarkko Sakkinen wrote:
> 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.
>
> Link: https://lore.kernel.org/linux-sgx/[email protected]/T/#u
> Fixes: 51ab30eb2ad4 ("x86/sgx: Replace section->init_laundry_list with sgx_dirty_page_list")
> Cc: [email protected] # v5.13+
> Reported-by: Paul Menzel <[email protected]>
> Signed-off-by: Jarkko Sakkinen <[email protected]>
Reviewed-by: Reinette Chatre <[email protected]>
Reinette
On Thu, Sep 08, 2022 at 12:53:55PM -0700, Reinette Chatre wrote:
>
>
> On 9/5/2022 5:02 PM, Jarkko Sakkinen wrote:
> > 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.
> >
> > Link: https://lore.kernel.org/linux-sgx/[email protected]/T/#u
> > Fixes: 51ab30eb2ad4 ("x86/sgx: Replace section->init_laundry_list with sgx_dirty_page_list")
> > Cc: [email protected] # v5.13+
> > Reported-by: Paul Menzel <[email protected]>
> > Signed-off-by: Jarkko Sakkinen <[email protected]>
>
> Reviewed-by: Reinette Chatre <[email protected]>
Thanks.
I also split down the long augment test also into pieces now,
as you requested, and I think it is now somewhat clean.
BR, Jarkko
The following commit has been merged into the x86/urgent branch of tip:
Commit-ID: 133e049a3f8c91b175029fb6a59b6039d5e79cba
Gitweb: https://git.kernel.org/tip/133e049a3f8c91b175029fb6a59b6039d5e79cba
Author: Jarkko Sakkinen <[email protected]>
AuthorDate: Tue, 06 Sep 2022 03:02:20 +03:00
Committer: Dave Hansen <[email protected]>
CommitterDate: Thu, 08 Sep 2022 13:27:44 -07:00
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: 51ab30eb2ad4 ("x86/sgx: Replace section->init_laundry_list with sgx_dirty_page_list")
Reported-by: Paul Menzel <[email protected]>
Signed-off-by: Jarkko Sakkinen <[email protected]>
Signed-off-by: Dave Hansen <[email protected]>
Reviewed-by: Reinette Chatre <[email protected]>
Cc: [email protected]
Link: https://lore.kernel.org/linux-sgx/[email protected]/T/#u
Link: https://lkml.kernel.org/r/[email protected]
---
arch/x86/kernel/cpu/sgx/main.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)
diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index 515e2a5..0aad028 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -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())