flex_array: convert element_nr formals to unsigned

It's problematic to allow signed element_nr's or total's to be passed as
part of the flex array API.

flex_array_alloc() allows total_nr_elements to be set to a negative
quantity, which is obviously erroneous.

flex_array_get() and flex_array_put() allows negative array indices in
dereferencing an array part, which could address memory mapped before
struct flex_array.

The fix is to convert all existing element_nr formals to be qualified as
unsigned.  Existing checks to compare it to total_nr_elements or the max
array size based on element_size need not be changed.

Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Dave Hansen <dave@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 4 deletions

diff --git a/include/linux/flex_array.h b/include/linux/flex_array.h
index 603160db7c98..45ff18491514 100644
--- a/include/linux/flex_array.h
+++ b/include/linux/flex_array.h
@@ -36,12 +36,14 @@ struct flex_array {
         .total_nr_elements = (total),   \
 } } }
 
-struct flex_array *flex_array_alloc(int element_size, int total, gfp_t flags);
-int flex_array_prealloc(struct flex_array *fa, int start, int end, gfp_t flags);
+struct flex_array *flex_array_alloc(int element_size, unsigned int total,
+                gfp_t flags);
+int flex_array_prealloc(struct flex_array *fa, unsigned int start,
+                unsigned int end, gfp_t flags);
 void flex_array_free(struct flex_array *fa);
 void flex_array_free_parts(struct flex_array *fa);
-int flex_array_put(struct flex_array *fa, int element_nr, void *src,
+int flex_array_put(struct flex_array *fa, unsigned int element_nr, void *src,
                 gfp_t flags);
-void *flex_array_get(struct flex_array *fa, int element_nr);
+void *flex_array_get(struct flex_array *fa, unsigned int element_nr);
 
 #endif /* _FLEX_ARRAY_H */