diff mbox series

[1/2] mm: kmsan: handle alloc failures in kmsan_vmap_pages_range_noflush()

Message ID 20230412145300.3651840-1-glider@google.com
State New
Headers
Series [1/2] mm: kmsan: handle alloc failures in kmsan_vmap_pages_range_noflush() |

Commit Message

Alexander Potapenko April 12, 2023, 2:52 p.m. UTC 
  As reported by Dipanjan Das, when KMSAN is used together with kernel
fault injection (or, generally, even without the latter), calls to
kcalloc() or __vmap_pages_range_noflush() may fail, leaving the
metadata mappings for the virtual mapping in an inconsistent state.
When these metadata mappings are accessed later, the kernel crashes.

To address the problem, we return a non-zero error code from
kmsan_vmap_pages_range_noflush() in the case of any allocation/mapping
failure inside it, and make vmap_pages_range_noflush() return an error
if KMSAN fails to allocate the metadata.

This patch also removes KMSAN_WARN_ON() from vmap_pages_range_noflush(),
as these allocation failures are not fatal anymore.

Reported-by: Dipanjan Das <mail.dipanjan.das@gmail.com>
Link: https://lore.kernel.org/linux-mm/CANX2M5ZRrRA64k0hOif02TjmY9kbbO2aCBPyq79es34RXZ=cAw@mail.gmail.com/
Fixes: b073d7f8aee4 ("mm: kmsan: maintain KMSAN metadata for page operations")
Signed-off-by: Alexander Potapenko <glider@google.com>
---
 include/linux/kmsan.h | 19 ++++++++++---------
 mm/kmsan/shadow.c     | 27 ++++++++++++++++++---------
 mm/vmalloc.c          |  6 +++++-
 3 files changed, 33 insertions(+), 19 deletions(-)

Comments

kernel test robot April 12, 2023, 6:27 p.m. UTC | #1 
Hi Alexander,

kernel test robot noticed the following build errors:

[auto build test ERROR on akpm-mm/mm-everything]

url:    https://github.com/intel-lab-lkp/linux/commits/Alexander-Potapenko/mm-kmsan-handle-alloc-failures-in-kmsan_ioremap_page_range/20230412-225414
base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link:    https://lore.kernel.org/r/20230412145300.3651840-1-glider%40google.com
patch subject: [PATCH 1/2] mm: kmsan: handle alloc failures in kmsan_vmap_pages_range_noflush()
config: i386-randconfig-a013 (https://download.01.org/0day-ci/archive/20230413/202304130223.epEIvA1E-lkp@intel.com/config)
compiler: clang version 14.0.6 (https://github.com/llvm/llvm-project f28c006a5895fc0e329fe15fead81e37457cb1d1)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/intel-lab-lkp/linux/commit/f8f0837563234abfae564b24278879d42d52a6e8
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Alexander-Potapenko/mm-kmsan-handle-alloc-failures-in-kmsan_ioremap_page_range/20230412-225414
        git checkout f8f0837563234abfae564b24278879d42d52a6e8
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=i386 olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=i386 prepare

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
| Link: https://lore.kernel.org/oe-kbuild-all/202304130223.epEIvA1E-lkp@intel.com/

All errors (new ones prefixed by >>):

   In file included from arch/x86/kernel/asm-offsets.c:14:
   In file included from include/linux/suspend.h:5:
   In file included from include/linux/swap.h:9:
   In file included from include/linux/memcontrol.h:22:
   In file included from include/linux/writeback.h:13:
   In file included from include/linux/blk_types.h:10:
   In file included from include/linux/bvec.h:10:
   In file included from include/linux/highmem.h:9:
>> include/linux/kmsan.h:291:1: error: non-void function does not return a value [-Werror,-Wreturn-type]
   }
   ^
   1 error generated.
   make[2]: *** [scripts/Makefile.build:114: arch/x86/kernel/asm-offsets.s] Error 1
   make[2]: Target 'prepare' not remade because of errors.
   make[1]: *** [Makefile:1286: prepare0] Error 2
   make[1]: Target 'prepare' not remade because of errors.
   make: *** [Makefile:226: __sub-make] Error 2
   make: Target 'prepare' not remade because of errors.


vim +291 include/linux/kmsan.h

68ef169a1dd20d Alexander Potapenko 2022-09-15  284  
f8f0837563234a Alexander Potapenko 2023-04-12  285  static inline int kmsan_vmap_pages_range_noflush(unsigned long start,
b073d7f8aee4eb Alexander Potapenko 2022-09-15  286  						 unsigned long end,
b073d7f8aee4eb Alexander Potapenko 2022-09-15  287  						 pgprot_t prot,
b073d7f8aee4eb Alexander Potapenko 2022-09-15  288  						 struct page **pages,
b073d7f8aee4eb Alexander Potapenko 2022-09-15  289  						 unsigned int page_shift)
b073d7f8aee4eb Alexander Potapenko 2022-09-15  290  {
b073d7f8aee4eb Alexander Potapenko 2022-09-15 @291  }
b073d7f8aee4eb Alexander Potapenko 2022-09-15  292
Andrew Morton April 12, 2023, 9:06 p.m. UTC | #2 
On Thu, 13 Apr 2023 02:27:19 +0800 kernel test robot <lkp@intel.com> wrote:

> Hi Alexander,
> 
> kernel test robot noticed the following build errors:
> 
> [auto build test ERROR on akpm-mm/mm-everything]
> 
> >> include/linux/kmsan.h:291:1: error: non-void function does not return a value [-Werror,-Wreturn-type]

Thanks, I'll do this:

--- a/include/linux/kmsan.h~mm-kmsan-handle-alloc-failures-in-kmsan_ioremap_page_range-fix
+++ a/include/linux/kmsan.h
@@ -289,6 +289,7 @@ static inline int kmsan_vmap_pages_range
 						 struct page **pages,
 						 unsigned int page_shift)
 {
+	return 0;
 }
 
 static inline void kmsan_vunmap_range_noflush(unsigned long start,
Alexander Potapenko April 13, 2023, 1:19 p.m. UTC | #3 
On Wed, Apr 12, 2023 at 11:06 PM Andrew Morton
<akpm@linux-foundation.org> wrote:
>
> On Thu, 13 Apr 2023 02:27:19 +0800 kernel test robot <lkp@intel.com> wrote:
>
> > Hi Alexander,
> >
> > kernel test robot noticed the following build errors:
> >
> > [auto build test ERROR on akpm-mm/mm-everything]
> >
> > >> include/linux/kmsan.h:291:1: error: non-void function does not return a value [-Werror,-Wreturn-type]
>
> Thanks, I'll do this:
Thanks!
I sent an updated version of the patch series, which includes your fix
as well as a couple more improvements (__must_check annotations in
particular)
diff mbox series

Patch

diff --git a/include/linux/kmsan.h b/include/linux/kmsan.h
index e38ae3c346184..a0769d4aad1c8 100644
--- a/include/linux/kmsan.h
+++ b/include/linux/kmsan.h
@@ -134,11 +134,12 @@  void kmsan_kfree_large(const void *ptr);
  * @page_shift:	page_shift passed to vmap_range_noflush().
  *
  * KMSAN maps shadow and origin pages of @pages into contiguous ranges in
- * vmalloc metadata address range.
+ * vmalloc metadata address range. Returns 0 on success, callers must check
+ * for non-zero return value.
  */
-void kmsan_vmap_pages_range_noflush(unsigned long start, unsigned long end,
-				    pgprot_t prot, struct page **pages,
-				    unsigned int page_shift);
+int kmsan_vmap_pages_range_noflush(unsigned long start, unsigned long end,
+				   pgprot_t prot, struct page **pages,
+				   unsigned int page_shift);
 
 /**
  * kmsan_vunmap_kernel_range_noflush() - Notify KMSAN about a vunmap.
@@ -281,11 +282,11 @@  static inline void kmsan_kfree_large(const void *ptr)
 {
 }
 
-static inline void kmsan_vmap_pages_range_noflush(unsigned long start,
-						  unsigned long end,
-						  pgprot_t prot,
-						  struct page **pages,
-						  unsigned int page_shift)
+static inline int kmsan_vmap_pages_range_noflush(unsigned long start,
+						 unsigned long end,
+						 pgprot_t prot,
+						 struct page **pages,
+						 unsigned int page_shift)
 {
 }
 
diff --git a/mm/kmsan/shadow.c b/mm/kmsan/shadow.c
index a787c04e9583c..b8bb95eea5e3d 100644
--- a/mm/kmsan/shadow.c
+++ b/mm/kmsan/shadow.c
@@ -216,27 +216,29 @@  void kmsan_free_page(struct page *page, unsigned int order)
 	kmsan_leave_runtime();
 }
 
-void kmsan_vmap_pages_range_noflush(unsigned long start, unsigned long end,
-				    pgprot_t prot, struct page **pages,
-				    unsigned int page_shift)
+int kmsan_vmap_pages_range_noflush(unsigned long start, unsigned long end,
+				   pgprot_t prot, struct page **pages,
+				   unsigned int page_shift)
 {
 	unsigned long shadow_start, origin_start, shadow_end, origin_end;
 	struct page **s_pages, **o_pages;
-	int nr, mapped;
+	int nr, mapped, err = 0;
 
 	if (!kmsan_enabled)
-		return;
+		return 0;
 
 	shadow_start = vmalloc_meta((void *)start, KMSAN_META_SHADOW);
 	shadow_end = vmalloc_meta((void *)end, KMSAN_META_SHADOW);
 	if (!shadow_start)
-		return;
+		return 0;
 
 	nr = (end - start) / PAGE_SIZE;
 	s_pages = kcalloc(nr, sizeof(*s_pages), GFP_KERNEL);
 	o_pages = kcalloc(nr, sizeof(*o_pages), GFP_KERNEL);
-	if (!s_pages || !o_pages)
+	if (!s_pages || !o_pages) {
+		err = -ENOMEM;
 		goto ret;
+	}
 	for (int i = 0; i < nr; i++) {
 		s_pages[i] = shadow_page_for(pages[i]);
 		o_pages[i] = origin_page_for(pages[i]);
@@ -249,10 +251,16 @@  void kmsan_vmap_pages_range_noflush(unsigned long start, unsigned long end,
 	kmsan_enter_runtime();
 	mapped = __vmap_pages_range_noflush(shadow_start, shadow_end, prot,
 					    s_pages, page_shift);
-	KMSAN_WARN_ON(mapped);
+	if (mapped) {
+		err = mapped;
+		goto ret;
+	}
 	mapped = __vmap_pages_range_noflush(origin_start, origin_end, prot,
 					    o_pages, page_shift);
-	KMSAN_WARN_ON(mapped);
+	if (mapped) {
+		err = mapped;
+		goto ret;
+	}
 	kmsan_leave_runtime();
 	flush_tlb_kernel_range(shadow_start, shadow_end);
 	flush_tlb_kernel_range(origin_start, origin_end);
@@ -262,6 +270,7 @@  void kmsan_vmap_pages_range_noflush(unsigned long start, unsigned long end,
 ret:
 	kfree(s_pages);
 	kfree(o_pages);
+	return err;
 }
 
 /* Allocate metadata for pages allocated at boot time. */
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index a50072066221a..1355d95cce1ca 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -605,7 +605,11 @@  int __vmap_pages_range_noflush(unsigned long addr, unsigned long end,
 int vmap_pages_range_noflush(unsigned long addr, unsigned long end,
 		pgprot_t prot, struct page **pages, unsigned int page_shift)
 {
-	kmsan_vmap_pages_range_noflush(addr, end, prot, pages, page_shift);
+	int ret = kmsan_vmap_pages_range_noflush(addr, end, prot, pages,
+						 page_shift);
+
+	if (ret)
+		return ret;
 	return __vmap_pages_range_noflush(addr, end, prot, pages, page_shift);
 }