Commit fdea03e1 authored by Alexander Potapenko's avatar Alexander Potapenko Committed by Andrew Morton
Browse files

mm: kmsan: handle alloc failures in kmsan_ioremap_page_range() 

Similarly to kmsan_vmap_pages_range_noflush(), kmsan_ioremap_page_range()
must also properly handle allocation/mapping failures.  In the case of
such, it must clean up the already created metadata mappings and return an
error code, so that the error can be propagated to ioremap_page_range(). 
Without doing so, KMSAN may silently fail to bring the metadata for the
page range into a consistent state, which will result in user-visible
crashes when trying to access them.

Link: https://lkml.kernel.org/r/20230413131223.4135168-2-glider@google.com


Fixes: b073d7f8 ("mm: kmsan: maintain KMSAN metadata for page operations")
Signed-off-by: default avatarAlexander Potapenko <glider@google.com>
Reported-by: default avatarDipanjan Das <mail.dipanjan.das@gmail.com>
  Link: https://lore.kernel.org/linux-mm/CANX2M5ZRrRA64k0hOif02TjmY9kbbO2aCBPyq79es34RXZ=cAw@mail.gmail.com/


Reviewed-by: default avatarMarco Elver <elver@google.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 47ebd031

include/linux/kmsan.h

+10 −9
Original line number Diff line number Diff line
@@ -160,9 +160,10 @@ void kmsan_vunmap_range_noflush(unsigned long start, unsigned long end); 
 * @page_shift:	page_shift argument passed to vmap_range_noflush().

 *

 * KMSAN creates new metadata pages for the physical pages mapped into the

 * virtual memory.

 * virtual memory. Returns 0 on success, callers must check for non-zero return

 * value.

 */

void kmsan_ioremap_page_range(unsigned long addr, unsigned long end,

int kmsan_ioremap_page_range(unsigned long addr, unsigned long end,

			     phys_addr_t phys_addr, pgprot_t prot,

			     unsigned int page_shift);
@@ -296,12 +297,12 @@ static inline void kmsan_vunmap_range_noflush(unsigned long start, 
{

}



static inline void kmsan_ioremap_page_range(unsigned long start,

static inline int kmsan_ioremap_page_range(unsigned long start,

					   unsigned long end,

					    phys_addr_t phys_addr,

					    pgprot_t prot,

					   phys_addr_t phys_addr, pgprot_t prot,

					   unsigned int page_shift)

{

	return 0;

}



static inline void kmsan_iounmap_page_range(unsigned long start,

mm/kmsan/hooks.c

+47 −8
Original line number Diff line number Diff line
@@ -148,35 +148,74 @@ void kmsan_vunmap_range_noflush(unsigned long start, unsigned long end) 
 * into the virtual memory. If those physical pages already had shadow/origin,

 * those are ignored.

 */

void kmsan_ioremap_page_range(unsigned long start, unsigned long end,

int kmsan_ioremap_page_range(unsigned long start, unsigned long end,

			     phys_addr_t phys_addr, pgprot_t prot,

			     unsigned int page_shift)

{

	gfp_t gfp_mask = GFP_KERNEL | __GFP_ZERO;

	struct page *shadow, *origin;

	unsigned long off = 0;

	int nr;

	int nr, err = 0, clean = 0, mapped;



	if (!kmsan_enabled || kmsan_in_runtime())

		return;

		return 0;



	nr = (end - start) / PAGE_SIZE;

	kmsan_enter_runtime();

	for (int i = 0; i < nr; i++, off += PAGE_SIZE) {

	for (int i = 0; i < nr; i++, off += PAGE_SIZE, clean = i) {

		shadow = alloc_pages(gfp_mask, 1);

		origin = alloc_pages(gfp_mask, 1);

		__vmap_pages_range_noflush(

		if (!shadow || !origin) {

			err = -ENOMEM;

			goto ret;

		}

		mapped = __vmap_pages_range_noflush(

			vmalloc_shadow(start + off),

			vmalloc_shadow(start + off + PAGE_SIZE), prot, &shadow,

			PAGE_SHIFT);

		__vmap_pages_range_noflush(

		if (mapped) {

			err = mapped;

			goto ret;

		}

		shadow = NULL;

		mapped = __vmap_pages_range_noflush(

			vmalloc_origin(start + off),

			vmalloc_origin(start + off + PAGE_SIZE), prot, &origin,

			PAGE_SHIFT);

		if (mapped) {

			__vunmap_range_noflush(

				vmalloc_shadow(start + off),

				vmalloc_shadow(start + off + PAGE_SIZE));

			err = mapped;

			goto ret;

		}

		origin = NULL;

	}

	/* Page mapping loop finished normally, nothing to clean up. */

	clean = 0;



ret:

	if (clean > 0) {

		/*

		 * Something went wrong. Clean up shadow/origin pages allocated

		 * on the last loop iteration, then delete mappings created

		 * during the previous iterations.

		 */

		if (shadow)

			__free_pages(shadow, 1);

		if (origin)

			__free_pages(origin, 1);

		__vunmap_range_noflush(

			vmalloc_shadow(start),

			vmalloc_shadow(start + clean * PAGE_SIZE));

		__vunmap_range_noflush(

			vmalloc_origin(start),

			vmalloc_origin(start + clean * PAGE_SIZE));

	}

	flush_cache_vmap(vmalloc_shadow(start), vmalloc_shadow(end));

	flush_cache_vmap(vmalloc_origin(start), vmalloc_origin(end));

	kmsan_leave_runtime();

	return err;

}



void kmsan_iounmap_page_range(unsigned long start, unsigned long end)

mm/vmalloc.c

+2 −2
Original line number Diff line number Diff line
@@ -313,7 +313,7 @@ int ioremap_page_range(unsigned long addr, unsigned long end, 
				 ioremap_max_page_shift);

	flush_cache_vmap(addr, end);

	if (!err)

		kmsan_ioremap_page_range(addr, end, phys_addr, prot,

		err = kmsan_ioremap_page_range(addr, end, phys_addr, prot,

					       ioremap_max_page_shift);

	return err;

}