lib/list_sort: do not pass bad pointers to cmp callback
If the original list is a POT in length, the first callback from line 73
will pass a==b both pointing to the original list_head. This is dangerous
because the 'list_sort()' user can use 'container_of()' and accesses the
"containing" object, which does not necessary exist for the list head. So
the user can access RAM which does not belong to him. If this is a write
access, we can end up with memory corruption.
Signed-off-by: Don Mullis <don.mullis@gmail.com>
Tested-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/lib/list_sort.c b/lib/list_sort.c
index 4b5cb79..a7616fa 100644
--- a/lib/list_sort.c
+++ b/lib/list_sort.c
@@ -70,7 +70,7 @@
* element comparison is needed, so the client's cmp()
* routine can invoke cond_resched() periodically.
*/
- (*cmp)(priv, tail, tail);
+ (*cmp)(priv, tail->next, tail->next);
tail->next->prev = tail;
tail = tail->next;
