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Message-Id: <20221003070722.390669625@linuxfoundation.org> Date: Mon, 3 Oct 2022 09:10:41 +0200 From: Greg Kroah-Hartman <gregkh@...uxfoundation.org> To: linux-kernel@...r.kernel.org Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, stable@...r.kernel.org, Paul Menzel <pmenzel@...gen.mpg.de>, Jarkko Sakkinen <jarkko@...nel.org>, Dave Hansen <dave.hansen@...ux.intel.com>, Reinette Chatre <reinette.chatre@...el.com> Subject: [PATCH 5.15 16/83] x86/sgx: Do not fail on incomplete sanitization on premature stop of ksgxd From: Jarkko Sakkinen <jarkko@...nel.org> commit 133e049a3f8c91b175029fb6a59b6039d5e79cba upstream. 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@...gen.mpg.de> Signed-off-by: Jarkko Sakkinen <jarkko@...nel.org> Signed-off-by: Dave Hansen <dave.hansen@...ux.intel.com> Reviewed-by: Reinette Chatre <reinette.chatre@...el.com> Cc: stable@...r.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 Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org> --- arch/x86/kernel/cpu/sgx/main.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) --- a/arch/x86/kernel/cpu/sgx/main.c +++ b/arch/x86/kernel/cpu/sgx/main.c @@ -46,9 +46,13 @@ 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; @@ -56,7 +60,7 @@ static void __sgx_sanitize_pages(struct /* 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); @@ -71,12 +75,14 @@ static void __sgx_sanitize_pages(struct } 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) @@ -427,10 +433,7 @@ 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())
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