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 <[email protected]> Cc: Dave Hansen <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
RyanHsu · Aug 27, 2009 · b62e408 · b62e408
1 parent 8e7ee27
commit b62e408
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Showing 2 changed files with 19 additions and 15 deletions.
diff --git 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 */
diff --git a/lib/flex_array.c b/lib/flex_array.c
@@ -99,7 +99,8 @@ static inline int elements_fit_in_base(struct flex_array *fa)
  * capacity in the base structure.  Also note that no effort is made
  * to efficiently pack objects across page boundaries.
  */
-struct flex_array *flex_array_alloc(int element_size, int total, gfp_t flags)
+struct flex_array *flex_array_alloc(int element_size, unsigned int total,
+					gfp_t flags)
 {
 	struct flex_array *ret;
 	int max_size = nr_base_part_ptrs() * __elements_per_part(element_size);
@@ -115,7 +116,8 @@ struct flex_array *flex_array_alloc(int element_size, int total, gfp_t flags)
 	return ret;
 }
 
-static int fa_element_to_part_nr(struct flex_array *fa, int element_nr)
+static int fa_element_to_part_nr(struct flex_array *fa,
+					unsigned int element_nr)
 {
 	return element_nr / __elements_per_part(fa->element_size);
 }
@@ -143,14 +145,12 @@ void flex_array_free(struct flex_array *fa)
 	kfree(fa);
 }
 
-static int fa_index_inside_part(struct flex_array *fa, int element_nr)
+static unsigned int index_inside_part(struct flex_array *fa,
+					unsigned int element_nr)
 {
-	return element_nr % __elements_per_part(fa->element_size);
-}
+	unsigned int part_offset;
 
-static int index_inside_part(struct flex_array *fa, int element_nr)
-{
-	int part_offset = fa_index_inside_part(fa, element_nr);
+	part_offset = element_nr % __elements_per_part(fa->element_size);
 	return part_offset * fa->element_size;
 }
 
@@ -185,7 +185,8 @@ __fa_get_part(struct flex_array *fa, int part_nr, gfp_t flags)
  *
  * Locking must be provided by the caller.
  */
-int flex_array_put(struct flex_array *fa, int element_nr, void *src, gfp_t flags)
+int flex_array_put(struct flex_array *fa, unsigned int element_nr, void *src,
+			gfp_t flags)
 {
 	int part_nr = fa_element_to_part_nr(fa, element_nr);
 	struct flex_array_part *part;
@@ -217,7 +218,8 @@ int flex_array_put(struct flex_array *fa, int element_nr, void *src, gfp_t flags
  *
  * Locking must be provided by the caller.
  */
-int flex_array_prealloc(struct flex_array *fa, int start, int end, gfp_t flags)
+int flex_array_prealloc(struct flex_array *fa, unsigned int start,
+			unsigned int end, gfp_t flags)
 {
 	int start_part;
 	int end_part;
@@ -248,7 +250,7 @@ int flex_array_prealloc(struct flex_array *fa, int start, int end, gfp_t flags)
  *
  * Locking must be provided by the caller.
  */
-void *flex_array_get(struct flex_array *fa, int element_nr)
+void *flex_array_get(struct flex_array *fa, unsigned int element_nr)
 {
 	int part_nr = fa_element_to_part_nr(fa, element_nr);
 	struct flex_array_part *part;