On 8/23/19 10:28 PM, Alexey Skidanov wrote:
In ion_cma_heap, the allocated buffer is represented by a single
struct scatterlist instance. The length field of this struct is
32 bit, hence the maximal size of requested buffer should be
less than 4GB.
The len paramer of the allocation function is 64 bit (on 64 bit systems).
Hence the requested size might be greater than 4GB and in this case
the field length of the struct scatterlist is initialized incorrectly.
To fix this, we check that requested size may fit into
the field length of the struct scatterlist
Is this a real issue that's actually possible to hit? Allocating
more than a 4GB region of CMA seems ill advised and likely to
throw off all the accounting.
Signed-off-by: Alexey Skidanov <alexey.skidanov@xxxxxxxxx>
---
drivers/staging/android/ion/ion.h | 5 +++++
drivers/staging/android/ion/ion_cma_heap.c | 3 +++
2 files changed, 8 insertions(+)
diff --git a/drivers/staging/android/ion/ion.h b/drivers/staging/android/ion/ion.h
index e291299..9dd7e20 100644
--- a/drivers/staging/android/ion/ion.h
+++ b/drivers/staging/android/ion/ion.h
@@ -21,6 +21,11 @@
#include "../uapi/ion.h"
+#define MAX_SCATTERLIST_LEN ({\
+ typeof(((struct scatterlist *)0)->length) v;\
+ v = -1;\
+ })
+
/**
* struct ion_buffer - metadata for a particular buffer
* @node: node in the ion_device buffers tree
diff --git a/drivers/staging/android/ion/ion_cma_heap.c b/drivers/staging/android/ion/ion_cma_heap.c
index bf65e67..d069719 100644
--- a/drivers/staging/android/ion/ion_cma_heap.c
+++ b/drivers/staging/android/ion/ion_cma_heap.c
@@ -36,6 +36,9 @@ static int ion_cma_allocate(struct ion_heap *heap, struct ion_buffer *buffer,
unsigned long align = get_order(size);
int ret;
+ if (size > MAX_SCATTERLIST_LEN)
+ return -EINVAL;
+
if (align > CONFIG_CMA_ALIGNMENT)
align = CONFIG_CMA_ALIGNMENT;
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