staging: ion: Fix overflow and list bugs in system heap

Fix a few bugs in ion_system_heap:

Initialize the list node in the info block.

Don't store size_remaining in a signed long, allocating >2GB
could overflow, resulting in a call to sg_alloc_table with
nents=0 which panics.  alloc_largest_available will never
return a block larger than size_remanining, so it can never
go negative.

Limit a single allocation to half of all memory.  Prevents a
large allocation from taking down the whole system.

Cc: Colin Cross <ccross@android.com>
Cc: Android Kernel Team <kernel-team@android.com>
Signed-off-by: Colin Cross <ccross@android.com>
[jstultz: Minor commit subject tweak]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 5 insertions, 1 deletions

diff --git a/drivers/staging/android/ion/ion_system_heap.c b/drivers/staging/android/ion/ion_system_heap.c
index 7f0729130d65..9849f3963e75 100644
--- a/drivers/staging/android/ion/ion_system_heap.c
+++ b/drivers/staging/android/ion/ion_system_heap.c
@@ -124,6 +124,7 @@ static struct page_info *alloc_largest_available(struct ion_system_heap *heap,
 
                 info->page = page;
                 info->order = orders[i];
+                INIT_LIST_HEAD(&info->list);
                 return info;
         }
         kfree(info);
@@ -145,12 +146,15 @@ static int ion_system_heap_allocate(struct ion_heap *heap,
         struct list_head pages;
         struct page_info *info, *tmp_info;
         int i = 0;
-        long size_remaining = PAGE_ALIGN(size);
+        unsigned long size_remaining = PAGE_ALIGN(size);
         unsigned int max_order = orders[0];
 
         if (align > PAGE_SIZE)
                 return -EINVAL;
 
+        if (size / PAGE_SIZE > totalram_pages / 2)
+                return -ENOMEM;
+
         INIT_LIST_HEAD(&pages);
         while (size_remaining > 0) {
                 info = alloc_largest_available(sys_heap, buffer, size_remaining,