[PATCH 5/7] staging: ion: Fix overflow and list bugs in system heap

From: John Stultz
Date: Tue Feb 04 2014 - 19:09:34 EST

From: Colin Cross <ccross@xxxxxxxxxxx>

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: Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Colin Cross <ccross@xxxxxxxxxxx>
Cc: Android Kernel Team <kernel-team@xxxxxxxxxxx>
Signed-off-by: Colin Cross <ccross@xxxxxxxxxxx>
[jstultz: Minor commit subject tweak]
Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx>
drivers/staging/android/ion/ion_system_heap.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/android/ion/ion_system_heap.c b/drivers/staging/android/ion/ion_system_heap.c
index 7f07291..9849f39 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;
@@ -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;
while (size_remaining > 0) {
info = alloc_largest_available(sys_heap, buffer, size_remaining,

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