| Message ID | 20190925143056.25853-3-vbabka@suse.cz (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | followups to debug_pagealloc improvements through page_owner | expand |
On Wed, Sep 25, 2019 at 04:30:51PM +0200, Vlastimil Babka wrote: > The commit 8974558f49a6 ("mm, page_owner, debug_pagealloc: save and dump > freeing stack trace") enhanced page_owner to also store freeing stack trace, > when debug_pagealloc is also enabled. KASAN would also like to do this [1] to > improve error reports to debug e.g. UAF issues. This patch therefore introduces > a helper config option PAGE_OWNER_FREE_STACK, which is enabled when PAGE_OWNER > and either of DEBUG_PAGEALLOC or KASAN is enabled. Boot-time, the free stack > saving is enabled when booting a KASAN kernel with page_owner=on, or non-KASAN > kernel with debug_pagealloc=on and page_owner=on. I would like to have an option to enable free stack for any PAGE_OWNER user at boot-time. Maybe drop CONFIG_PAGE_OWNER_FREE_STACK completely and add page_owner_free=on cmdline option as yet another way to trigger 'static_branch_enable(&page_owner_free_stack)'? > [1] https://bugzilla.kernel.org/show_bug.cgi?id=203967 > > Suggested-by: Dmitry Vyukov <dvyukov@google.com> > Suggested-by: Walter Wu <walter-zh.wu@mediatek.com> > Suggested-by: Andrey Ryabinin <aryabinin@virtuozzo.com> > Signed-off-by: Vlastimil Babka <vbabka@suse.cz> > Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com> > --- > Documentation/dev-tools/kasan.rst | 4 ++++ > mm/Kconfig.debug | 4 ++++ > mm/page_owner.c | 31 ++++++++++++++++++------------- > 3 files changed, 26 insertions(+), 13 deletions(-) > > diff --git a/Documentation/dev-tools/kasan.rst b/Documentation/dev-tools/kasan.rst > index b72d07d70239..434e605030e9 100644 > --- a/Documentation/dev-tools/kasan.rst > +++ b/Documentation/dev-tools/kasan.rst > @@ -41,6 +41,10 @@ smaller binary while the latter is 1.1 - 2 times faster. > Both KASAN modes work with both SLUB and SLAB memory allocators. > For better bug detection and nicer reporting, enable CONFIG_STACKTRACE. > > +To augment reports with last allocation and freeing stack of the physical > +page, it is recommended to configure kernel also with CONFIG_PAGE_OWNER = y Nit: remove spaces around '=' or write "with CONFIG_PAGE_OWNER enabled". > +and boot with page_owner=on. > + > To disable instrumentation for specific files or directories, add a line > similar to the following to the respective kernel Makefile: > > diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug > index 327b3ebf23bf..1ea247da3322 100644 > --- a/mm/Kconfig.debug > +++ b/mm/Kconfig.debug > @@ -62,6 +62,10 @@ config PAGE_OWNER > > If unsure, say N. > > +config PAGE_OWNER_FREE_STACK > + def_bool KASAN || DEBUG_PAGEALLOC > + depends on PAGE_OWNER > + > config PAGE_POISONING > bool "Poison pages after freeing" > select PAGE_POISONING_NO_SANITY if HIBERNATION > diff --git a/mm/page_owner.c b/mm/page_owner.c > index d3cf5d336ccf..f3aeec78822f 100644 > --- a/mm/page_owner.c > +++ b/mm/page_owner.c > @@ -24,13 +24,14 @@ struct page_owner { > short last_migrate_reason; > gfp_t gfp_mask; > depot_stack_handle_t handle; > -#ifdef CONFIG_DEBUG_PAGEALLOC > +#ifdef CONFIG_PAGE_OWNER_FREE_STACK > depot_stack_handle_t free_handle; > #endif > }; > > static bool page_owner_disabled = true; > DEFINE_STATIC_KEY_FALSE(page_owner_inited); > +static DEFINE_STATIC_KEY_FALSE(page_owner_free_stack); > > static depot_stack_handle_t dummy_handle; > static depot_stack_handle_t failure_handle; > @@ -91,6 +92,8 @@ static void init_page_owner(void) > register_failure_stack(); > register_early_stack(); > static_branch_enable(&page_owner_inited); > + if (IS_ENABLED(CONFIG_KASAN) || debug_pagealloc_enabled()) > + static_branch_enable(&page_owner_free_stack); > init_early_allocated_pages(); > } > > @@ -148,11 +151,11 @@ void __reset_page_owner(struct page *page, unsigned int order) > { > int i; > struct page_ext *page_ext; > -#ifdef CONFIG_DEBUG_PAGEALLOC > +#ifdef CONFIG_PAGE_OWNER_FREE_STACK > depot_stack_handle_t handle = 0; > struct page_owner *page_owner; > > - if (debug_pagealloc_enabled()) > + if (static_branch_unlikely(&page_owner_free_stack)) > handle = save_stack(GFP_NOWAIT | __GFP_NOWARN); > #endif > > @@ -161,8 +164,8 @@ void __reset_page_owner(struct page *page, unsigned int order) > return; > for (i = 0; i < (1 << order); i++) { > __clear_bit(PAGE_EXT_OWNER_ACTIVE, &page_ext->flags); > -#ifdef CONFIG_DEBUG_PAGEALLOC > - if (debug_pagealloc_enabled()) { > +#ifdef CONFIG_PAGE_OWNER_FREE_STACK > + if (static_branch_unlikely(&page_owner_free_stack)) { > page_owner = get_page_owner(page_ext); > page_owner->free_handle = handle; > } > @@ -450,14 +453,16 @@ void __dump_page_owner(struct page *page) > stack_trace_print(entries, nr_entries, 0); > } > > -#ifdef CONFIG_DEBUG_PAGEALLOC > - handle = READ_ONCE(page_owner->free_handle); > - if (!handle) { > - pr_alert("page_owner free stack trace missing\n"); > - } else { > - nr_entries = stack_depot_fetch(handle, &entries); > - pr_alert("page last free stack trace:\n"); > - stack_trace_print(entries, nr_entries, 0); > +#ifdef CONFIG_PAGE_OWNER_FREE_STACK > + if (static_branch_unlikely(&page_owner_free_stack)) { > + handle = READ_ONCE(page_owner->free_handle); > + if (!handle) { > + pr_alert("page_owner free stack trace missing\n"); > + } else { > + nr_entries = stack_depot_fetch(handle, &entries); > + pr_alert("page last free stack trace:\n"); > + stack_trace_print(entries, nr_entries, 0); > + } > } > #endif > > -- > 2.23.0 > >
On 9/26/19 11:16 AM, Kirill A. Shutemov wrote: > On Wed, Sep 25, 2019 at 04:30:51PM +0200, Vlastimil Babka wrote: >> The commit 8974558f49a6 ("mm, page_owner, debug_pagealloc: save and dump >> freeing stack trace") enhanced page_owner to also store freeing stack trace, >> when debug_pagealloc is also enabled. KASAN would also like to do this [1] to >> improve error reports to debug e.g. UAF issues. This patch therefore introduces >> a helper config option PAGE_OWNER_FREE_STACK, which is enabled when PAGE_OWNER >> and either of DEBUG_PAGEALLOC or KASAN is enabled. Boot-time, the free stack >> saving is enabled when booting a KASAN kernel with page_owner=on, or non-KASAN >> kernel with debug_pagealloc=on and page_owner=on. > > I would like to have an option to enable free stack for any PAGE_OWNER > user at boot-time. > > Maybe drop CONFIG_PAGE_OWNER_FREE_STACK completely and add > page_owner_free=on cmdline option as yet another way to trigger > 'static_branch_enable(&page_owner_free_stack)'? Well, if you think it's useful, I'm not opposed.
diff --git a/Documentation/dev-tools/kasan.rst b/Documentation/dev-tools/kasan.rst index b72d07d70239..434e605030e9 100644 --- a/Documentation/dev-tools/kasan.rst +++ b/Documentation/dev-tools/kasan.rst @@ -41,6 +41,10 @@ smaller binary while the latter is 1.1 - 2 times faster. Both KASAN modes work with both SLUB and SLAB memory allocators. For better bug detection and nicer reporting, enable CONFIG_STACKTRACE. +To augment reports with last allocation and freeing stack of the physical +page, it is recommended to configure kernel also with CONFIG_PAGE_OWNER = y +and boot with page_owner=on. + To disable instrumentation for specific files or directories, add a line similar to the following to the respective kernel Makefile: diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug index 327b3ebf23bf..1ea247da3322 100644 --- a/mm/Kconfig.debug +++ b/mm/Kconfig.debug @@ -62,6 +62,10 @@ config PAGE_OWNER If unsure, say N. +config PAGE_OWNER_FREE_STACK + def_bool KASAN || DEBUG_PAGEALLOC + depends on PAGE_OWNER + config PAGE_POISONING bool "Poison pages after freeing" select PAGE_POISONING_NO_SANITY if HIBERNATION diff --git a/mm/page_owner.c b/mm/page_owner.c index d3cf5d336ccf..f3aeec78822f 100644 --- a/mm/page_owner.c +++ b/mm/page_owner.c @@ -24,13 +24,14 @@ struct page_owner { short last_migrate_reason; gfp_t gfp_mask; depot_stack_handle_t handle; -#ifdef CONFIG_DEBUG_PAGEALLOC +#ifdef CONFIG_PAGE_OWNER_FREE_STACK depot_stack_handle_t free_handle; #endif }; static bool page_owner_disabled = true; DEFINE_STATIC_KEY_FALSE(page_owner_inited); +static DEFINE_STATIC_KEY_FALSE(page_owner_free_stack); static depot_stack_handle_t dummy_handle; static depot_stack_handle_t failure_handle; @@ -91,6 +92,8 @@ static void init_page_owner(void) register_failure_stack(); register_early_stack(); static_branch_enable(&page_owner_inited); + if (IS_ENABLED(CONFIG_KASAN) || debug_pagealloc_enabled()) + static_branch_enable(&page_owner_free_stack); init_early_allocated_pages(); } @@ -148,11 +151,11 @@ void __reset_page_owner(struct page *page, unsigned int order) { int i; struct page_ext *page_ext; -#ifdef CONFIG_DEBUG_PAGEALLOC +#ifdef CONFIG_PAGE_OWNER_FREE_STACK depot_stack_handle_t handle = 0; struct page_owner *page_owner; - if (debug_pagealloc_enabled()) + if (static_branch_unlikely(&page_owner_free_stack)) handle = save_stack(GFP_NOWAIT | __GFP_NOWARN); #endif @@ -161,8 +164,8 @@ void __reset_page_owner(struct page *page, unsigned int order) return; for (i = 0; i < (1 << order); i++) { __clear_bit(PAGE_EXT_OWNER_ACTIVE, &page_ext->flags); -#ifdef CONFIG_DEBUG_PAGEALLOC - if (debug_pagealloc_enabled()) { +#ifdef CONFIG_PAGE_OWNER_FREE_STACK + if (static_branch_unlikely(&page_owner_free_stack)) { page_owner = get_page_owner(page_ext); page_owner->free_handle = handle; } @@ -450,14 +453,16 @@ void __dump_page_owner(struct page *page) stack_trace_print(entries, nr_entries, 0); } -#ifdef CONFIG_DEBUG_PAGEALLOC - handle = READ_ONCE(page_owner->free_handle); - if (!handle) { - pr_alert("page_owner free stack trace missing\n"); - } else { - nr_entries = stack_depot_fetch(handle, &entries); - pr_alert("page last free stack trace:\n"); - stack_trace_print(entries, nr_entries, 0); +#ifdef CONFIG_PAGE_OWNER_FREE_STACK + if (static_branch_unlikely(&page_owner_free_stack)) { + handle = READ_ONCE(page_owner->free_handle); + if (!handle) { + pr_alert("page_owner free stack trace missing\n"); + } else { + nr_entries = stack_depot_fetch(handle, &entries); + pr_alert("page last free stack trace:\n"); + stack_trace_print(entries, nr_entries, 0); + } } #endif
The commit 8974558f49a6 ("mm, page_owner, debug_pagealloc: save and dump freeing stack trace") enhanced page_owner to also store freeing stack trace, when debug_pagealloc is also enabled. KASAN would also like to do this [1] to improve error reports to debug e.g. UAF issues. This patch therefore introduces a helper config option PAGE_OWNER_FREE_STACK, which is enabled when PAGE_OWNER and either of DEBUG_PAGEALLOC or KASAN is enabled. Boot-time, the free stack saving is enabled when booting a KASAN kernel with page_owner=on, or non-KASAN kernel with debug_pagealloc=on and page_owner=on. [1] https://bugzilla.kernel.org/show_bug.cgi?id=203967 Suggested-by: Dmitry Vyukov <dvyukov@google.com> Suggested-by: Walter Wu <walter-zh.wu@mediatek.com> Suggested-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com> --- Documentation/dev-tools/kasan.rst | 4 ++++ mm/Kconfig.debug | 4 ++++ mm/page_owner.c | 31 ++++++++++++++++++------------- 3 files changed, 26 insertions(+), 13 deletions(-)