From: Andrey Konovalov <andreyknvl@google.com> To: Andrew Morton <akpm@linux-foundation.org> Cc: Alexander Potapenko <glider@google.com>, Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will.deacon@arm.com>, Vincenzo Frascino <vincenzo.frascino@arm.com>, Dmitry Vyukov <dvyukov@google.com>, Andrey Ryabinin <aryabinin@virtuozzo.com>, Marco Elver <elver@google.com>, Peter Collingbourne <pcc@google.com>, Evgenii Stepanov <eugenis@google.com>, Branislav Rankov <Branislav.Rankov@arm.com>, Kevin Brodsky <kevin.brodsky@arm.com>, kasan-dev <kasan-dev@googlegroups.com>, Linux ARM <linux-arm-kernel@lists.infradead.org>, Linux Memory Management List <linux-mm@kvack.org>, LKML <linux-kernel@vger.kernel.org>, stable <stable@vger.kernel.org> Subject: Re: [PATCH v2] kasan, mm: fix crash with HW_TAGS and DEBUG_PAGEALLOC Date: Sat, 6 Mar 2021 00:54:32 +0100 [thread overview] Message-ID: <CAAeHK+yHf7p9H_EiPVfA9qadGU_6x0RrKwX-WjKrHEFz+xFEbg@mail.gmail.com> (raw) In-Reply-To: <20210305154956.3bbfcedab3f549b708d5e2fa@linux-foundation.org> On Sat, Mar 6, 2021 at 12:50 AM Andrew Morton <akpm@linux-foundation.org> wrote: > > On Sat, 6 Mar 2021 00:36:33 +0100 Andrey Konovalov <andreyknvl@google.com> wrote: > > > Currently, kasan_free_nondeferred_pages()->kasan_free_pages() is called > > after debug_pagealloc_unmap_pages(). This causes a crash when > > debug_pagealloc is enabled, as HW_TAGS KASAN can't set tags on an > > unmapped page. > > > > This patch puts kasan_free_nondeferred_pages() before > > debug_pagealloc_unmap_pages() and arch_free_page(), which can also make > > the page unavailable. > > > > ... > > > > --- a/mm/page_alloc.c > > +++ b/mm/page_alloc.c > > @@ -1304,6 +1304,12 @@ static __always_inline bool free_pages_prepare(struct page *page, > > > > kernel_poison_pages(page, 1 << order); > > > > + /* > > + * With hardware tag-based KASAN, memory tags must be set before the > > + * page becomes unavailable via debug_pagealloc or arch_free_page. > > + */ > > + kasan_free_nondeferred_pages(page, order, fpi_flags); > > + > > /* > > * arch_free_page() can make the page's contents inaccessible. s390 > > * does this. So nothing which can access the page's contents should > > @@ -1313,8 +1319,6 @@ static __always_inline bool free_pages_prepare(struct page *page, > > > > debug_pagealloc_unmap_pages(page, 1 << order); > > > > - kasan_free_nondeferred_pages(page, order, fpi_flags); > > - > > return true; > > } > > kasan_free_nondeferred_pages() has only two args in current mainline. Ah, yes, forgot to mention: this goes on top of: kasan: initialize shadow to TAG_INVALID for SW_TAGS mm, kasan: don't poison boot memory with tag-based modes > > I fixed that in the obvious manner... Thanks! If you changed this patch, you'll also need to change the other one though.
WARNING: multiple messages have this Message-ID (diff)
From: Andrey Konovalov <andreyknvl@google.com> To: Andrew Morton <akpm@linux-foundation.org> Cc: Alexander Potapenko <glider@google.com>, Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will.deacon@arm.com>, Vincenzo Frascino <vincenzo.frascino@arm.com>, Dmitry Vyukov <dvyukov@google.com>, Andrey Ryabinin <aryabinin@virtuozzo.com>, Marco Elver <elver@google.com>, Peter Collingbourne <pcc@google.com>, Evgenii Stepanov <eugenis@google.com>, Branislav Rankov <Branislav.Rankov@arm.com>, Kevin Brodsky <kevin.brodsky@arm.com>, kasan-dev <kasan-dev@googlegroups.com>, Linux ARM <linux-arm-kernel@lists.infradead.org>, Linux Memory Management List <linux-mm@kvack.org>, LKML <linux-kernel@vger.kernel.org>, stable <stable@vger.kernel.org> Subject: Re: [PATCH v2] kasan, mm: fix crash with HW_TAGS and DEBUG_PAGEALLOC Date: Sat, 6 Mar 2021 00:54:32 +0100 [thread overview] Message-ID: <CAAeHK+yHf7p9H_EiPVfA9qadGU_6x0RrKwX-WjKrHEFz+xFEbg@mail.gmail.com> (raw) In-Reply-To: <20210305154956.3bbfcedab3f549b708d5e2fa@linux-foundation.org> On Sat, Mar 6, 2021 at 12:50 AM Andrew Morton <akpm@linux-foundation.org> wrote: > > On Sat, 6 Mar 2021 00:36:33 +0100 Andrey Konovalov <andreyknvl@google.com> wrote: > > > Currently, kasan_free_nondeferred_pages()->kasan_free_pages() is called > > after debug_pagealloc_unmap_pages(). This causes a crash when > > debug_pagealloc is enabled, as HW_TAGS KASAN can't set tags on an > > unmapped page. > > > > This patch puts kasan_free_nondeferred_pages() before > > debug_pagealloc_unmap_pages() and arch_free_page(), which can also make > > the page unavailable. > > > > ... > > > > --- a/mm/page_alloc.c > > +++ b/mm/page_alloc.c > > @@ -1304,6 +1304,12 @@ static __always_inline bool free_pages_prepare(struct page *page, > > > > kernel_poison_pages(page, 1 << order); > > > > + /* > > + * With hardware tag-based KASAN, memory tags must be set before the > > + * page becomes unavailable via debug_pagealloc or arch_free_page. > > + */ > > + kasan_free_nondeferred_pages(page, order, fpi_flags); > > + > > /* > > * arch_free_page() can make the page's contents inaccessible. s390 > > * does this. So nothing which can access the page's contents should > > @@ -1313,8 +1319,6 @@ static __always_inline bool free_pages_prepare(struct page *page, > > > > debug_pagealloc_unmap_pages(page, 1 << order); > > > > - kasan_free_nondeferred_pages(page, order, fpi_flags); > > - > > return true; > > } > > kasan_free_nondeferred_pages() has only two args in current mainline. Ah, yes, forgot to mention: this goes on top of: kasan: initialize shadow to TAG_INVALID for SW_TAGS mm, kasan: don't poison boot memory with tag-based modes > > I fixed that in the obvious manner... Thanks! If you changed this patch, you'll also need to change the other one though. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2021-03-05 23:55 UTC|newest] Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-03-05 23:36 [PATCH v2] kasan, mm: fix crash with HW_TAGS and DEBUG_PAGEALLOC Andrey Konovalov 2021-03-05 23:36 ` Andrey Konovalov 2021-03-05 23:36 ` Andrey Konovalov 2021-03-05 23:49 ` Andrew Morton 2021-03-05 23:49 ` Andrew Morton 2021-03-05 23:54 ` Andrey Konovalov [this message] 2021-03-05 23:54 ` Andrey Konovalov 2021-03-05 23:54 ` Andrey Konovalov 2021-03-05 23:54 ` Andrey Konovalov 2021-03-05 23:54 ` Andrey Konovalov 2021-03-05 23:54 ` Andrey Konovalov 2021-03-06 1:27 ` Andrew Morton 2021-03-06 1:27 ` Andrew Morton
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