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treewide: Change list_sort to use const pointers

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list_sort() internally casts the comparison function passed to it
to a different type with constant struct list_head pointers, and
uses this pointer to call the functions, which trips indirect call
Control-Flow Integrity (CFI) checking.

Instead of removing the consts, this change defines the
list_cmp_func_t type and changes the comparison function types of
all list_sort() callers to use const pointers, thus avoiding type
mismatches.

Suggested-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210408182843.1754385-10-samitolvanen@google.com
This commit is contained in:
Sami Tolvanen
2021-04-08 11:28:34 -07:00
committed by Kees Cook
parent 9f5b400998
commit 4f0f586bf0
41 changed files with 90 additions and 72 deletions
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17
lib/list_sort.c
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@@ -7,16 +7,13 @@
#include <linux/list_sort.h>
#include <linux/list.h>
typedef int __attribute__((nonnull(2,3))) (*cmp_func)(void *,
struct list_head const *, struct list_head const *);
/*
* Returns a list organized in an intermediate format suited
* to chaining of merge() calls: null-terminated, no reserved or
* sentinel head node, "prev" links not maintained.
*/
__attribute__((nonnull(2,3,4)))
static struct list_head *merge(void *priv, cmp_func cmp,
static struct list_head *merge(void *priv, list_cmp_func_t cmp,
struct list_head *a, struct list_head *b)
{
struct list_head *head, **tail = &head;
@@ -52,7 +49,7 @@ static struct list_head *merge(void *priv, cmp_func cmp,
* throughout.
*/
__attribute__((nonnull(2,3,4,5)))
static void merge_final(void *priv, cmp_func cmp, struct list_head *head,
static void merge_final(void *priv, list_cmp_func_t cmp, struct list_head *head,
struct list_head *a, struct list_head *b)
{
struct list_head *tail = head;
@@ -185,9 +182,7 @@ static void merge_final(void *priv, cmp_func cmp, struct list_head *head,
* 2^(k+1) - 1 (second merge of case 5 when x == 2^(k-1) - 1).
*/
__attribute__((nonnull(2,3)))
void list_sort(void *priv, struct list_head *head,
int (*cmp)(void *priv, struct list_head *a,
struct list_head *b))
void list_sort(void *priv, struct list_head *head, list_cmp_func_t cmp)
{
struct list_head *list = head->next, *pending = NULL;
size_t count = 0; /* Count of pending */
@@ -227,7 +222,7 @@ void list_sort(void *priv, struct list_head *head,
if (likely(bits)) {
struct list_head *a = *tail, *b = a->prev;
a = merge(priv, (cmp_func)cmp, b, a);
a = merge(priv, cmp, b, a);
/* Install the merged result in place of the inputs */
a->prev = b->prev;
*tail = a;
@@ -249,10 +244,10 @@ void list_sort(void *priv, struct list_head *head,
if (!next)
break;
list = merge(priv, (cmp_func)cmp, pending, list);
list = merge(priv, cmp, pending, list);
pending = next;
}
/* The final merge, rebuilding prev links */
merge_final(priv, (cmp_func)cmp, head, pending, list);
merge_final(priv, cmp, head, pending, list);
}
EXPORT_SYMBOL(list_sort);