of: fix kmemleak crash caused by imbalance in early memory reservation

Marc Gonzalez reported the following kmemleak crash:

  Unable to handle kernel paging request at virtual address ffffffc021e00000
  Mem abort info:
    ESR = 0x96000006
    Exception class = DABT (current EL), IL = 32 bits
    SET = 0, FnV = 0
    EA = 0, S1PTW = 0
  Data abort info:
    ISV = 0, ISS = 0x00000006
    CM = 0, WnR = 0
  swapper pgtable: 4k pages, 39-bit VAs, pgdp = (____ptrval____) [ffffffc021e00000] pgd=000000017e3ba803, pud=000000017e3ba803, pmd=0000000000000000
  Internal error: Oops: 96000006 [#1] PREEMPT SMP
  Modules linked in:
  CPU: 6 PID: 523 Comm: kmemleak Tainted: G S      W         5.0.0-rc1 #13
  Hardware name: Qualcomm Technologies, Inc. MSM8998 v1 MTP (DT)
  pstate: 80000085 (Nzcv daIf -PAN -UAO)
  pc : scan_block+0x70/0x190
  lr : scan_block+0x6c/0x190
  Process kmemleak (pid: 523, stack limit = 0x(____ptrval____))
  Call trace:
   scan_block+0x70/0x190
   scan_gray_list+0x108/0x1c0
   kmemleak_scan+0x33c/0x7c0
   kmemleak_scan_thread+0x98/0xf0
   kthread+0x11c/0x120
   ret_from_fork+0x10/0x1c
  Code: f9000fb4 d503201f 97ffffd2 35000580 (f9400260)

The crash happens when a no-map area is allocated in
early_init_dt_alloc_reserved_memory_arch().  The allocated region is
registered with kmemleak, but it is then removed from memblock using
memblock_remove() that is not kmemleak-aware.

Replacing memblock_phys_alloc_range() with memblock_find_in_range()
makes sure that the allocated memory is not added to kmemleak and then
memblock_remove()'ing this memory is safe.

As a bonus, since memblock_find_in_range() ensures the allocation in the
specified range, the bounds check can be removed.

[rppt@linux.ibm.com: of: fix parameters order for call to memblock_find_in_range()]
  Link: http://lkml.kernel.org/r/20190221112619.GC32004@rapoport-lnx
Link: http://lkml.kernel.org/r/20190213181921.GB15270@rapoport-lnx
Fixes: 3f0c8206 ("drivers: of: add initialization code for dynamic reserved memory")
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Prateek Patel <prpatel@nvidia.com>
Tested-by: Marc Gonzalez <marc.w.gonzalez@free.fr>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Frank Rowand <frowand.list@gmail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/of/of_reserved_mem.c

@@ -34,22 +34,15 @@ static int __init early_init_dt_alloc_reserved_memory_arch(phys_addr_t size,
 
 	end = !end ? MEMBLOCK_ALLOC_ANYWHERE : end;
 	align = !align ? SMP_CACHE_BYTES : align;
-	base = memblock_phys_alloc_range(size, align, 0, end);
+	base = memblock_find_in_range(start, end, size, align);
 	if (!base)
 		return -ENOMEM;
 
-	/*
-	 * Check if the allocated region fits in to start..end window
-	 */
-	if (base < start) {
-		memblock_free(base, size);
-		return -ENOMEM;
-	}
-
 	*res_base = base;
 	if (nomap)
 		return memblock_remove(base, size);
-	return 0;
+
+	return memblock_reserve(base, size);
 }
 
 /**