On 9/4/19 8:51 AM, Walter Wu wrote: > This patch is KASAN report adds the alloc/free stacks for page allocator > in order to help programmer to see memory corruption caused by page. > > By default, KASAN doesn't record alloc/free stack for page allocator. > It is difficult to fix up page use-after-free issue. > > This feature depends on page owner to record the last stack of pages. > It is very helpful for solving the page use-after-free or out-of-bound. > > KASAN report will show the last stack of page, it may be: > a) If page is in-use state, then it prints alloc stack. > It is useful to fix up page out-of-bound issue. I expect this will conflict both in syntax and semantics with my series [1] that adds the freeing stack to page_owner when used together with debug_pagealloc, and it's now in mmotm. Glad others see the need as well :) Perhaps you could review the series, see if it fulfils your usecase (AFAICS the series should be a superset, by storing both stacks at once), and perhaps either make KASAN enable debug_pagealloc, or turn KASAN into an alternative enabler of the functionality there? Thanks, Vlastimil [1] https://lore.kernel.org/linux-mm/20190820131828.22684-1-vbabka@xxxxxxx/t/#u > BUG: KASAN: slab-out-of-bounds in kmalloc_pagealloc_oob_right+0x88/0x90 > Write of size 1 at addr ffffffc0d64ea00a by task cat/115 > ... > Allocation stack of page: > prep_new_page+0x1a0/0x1d8 > get_page_from_freelist+0xd78/0x2748 > __alloc_pages_nodemask+0x1d4/0x1978 > kmalloc_order+0x28/0x58 > kmalloc_order_trace+0x28/0xe0 > kmalloc_pagealloc_oob_right+0x2c/0x90 > > b) If page is freed state, then it prints free stack. > It is useful to fix up page use-after-free issue. > > BUG: KASAN: use-after-free in kmalloc_pagealloc_uaf+0x70/0x80 > Write of size 1 at addr ffffffc0d651c000 by task cat/115 > ... > Free stack of page: > kasan_free_pages+0x68/0x70 > __free_pages_ok+0x3c0/0x1328 > __free_pages+0x50/0x78 > kfree+0x1c4/0x250 > kmalloc_pagealloc_uaf+0x38/0x80 > > > This has been discussed, please refer below link. > https://bugzilla.kernel.org/show_bug.cgi?id=203967 > > Signed-off-by: Walter Wu <walter-zh.wu@xxxxxxxxxxxx> > --- > lib/Kconfig.kasan | 9 +++++++++ > mm/kasan/common.c | 6 ++++++ > 2 files changed, 15 insertions(+) > > diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan > index 4fafba1a923b..ba17f706b5f8 100644 > --- a/lib/Kconfig.kasan > +++ b/lib/Kconfig.kasan > @@ -135,6 +135,15 @@ config KASAN_S390_4_LEVEL_PAGING > to 3TB of RAM with KASan enabled). This options allows to force > 4-level paging instead. > > +config KASAN_DUMP_PAGE > + bool "Dump the page last stack information" > + depends on KASAN && PAGE_OWNER > + help > + By default, KASAN doesn't record alloc/free stack for page allocator. > + It is difficult to fix up page use-after-free issue. > + This feature depends on page owner to record the last stack of page. > + It is very helpful for solving the page use-after-free or out-of-bound. > + > config TEST_KASAN > tristate "Module for testing KASAN for bug detection" > depends on m && KASAN > diff --git a/mm/kasan/common.c b/mm/kasan/common.c > index 2277b82902d8..2a32474efa74 100644 > --- a/mm/kasan/common.c > +++ b/mm/kasan/common.c > @@ -35,6 +35,7 @@ > #include <linux/vmalloc.h> > #include <linux/bug.h> > #include <linux/uaccess.h> > +#include <linux/page_owner.h> > > #include "kasan.h" > #include "../slab.h" > @@ -227,6 +228,11 @@ void kasan_alloc_pages(struct page *page, unsigned int order) > > void kasan_free_pages(struct page *page, unsigned int order) > { > +#ifdef CONFIG_KASAN_DUMP_PAGE > + gfp_t gfp_flags = GFP_KERNEL; > + > + set_page_owner(page, order, gfp_flags); > +#endif > if (likely(!PageHighMem(page))) > kasan_poison_shadow(page_address(page), > PAGE_SIZE << order, >
