lib/list_debug.c: print unmangled addresses

The entire point of printing the pointers in list_debug is to see if
there's any useful information in them (eg poison values, ASCII, etc);
obscuring them to see if they compare equal makes them much less useful.
If an attacker can force this message to be printed, we've already lost.

Link: http://lkml.kernel.org/r/20180401223237.GV13332@bombadil.infradead.orgSigned-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Reviewed-by: Tobin C. Harding <me@tobin.cc>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Eric Biggers <ebiggers3@gmail.com>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

lib/list_debug.c

@@ -21,13 +21,13 @@ bool __list_add_valid(struct list_head *new, struct list_head *prev,
 		      struct list_head *next)
 {
 	if (CHECK_DATA_CORRUPTION(next->prev != prev,
-			"list_add corruption. next->prev should be prev (%p), but was %p. (next=%p).\n",
+			"list_add corruption. next->prev should be prev (%px), but was %px. (next=%px).\n",
 			prev, next->prev, next) ||
 	    CHECK_DATA_CORRUPTION(prev->next != next,
-			"list_add corruption. prev->next should be next (%p), but was %p. (prev=%p).\n",
+			"list_add corruption. prev->next should be next (%px), but was %px. (prev=%px).\n",
 			next, prev->next, prev) ||
 	    CHECK_DATA_CORRUPTION(new == prev || new == next,
-			"list_add double add: new=%p, prev=%p, next=%p.\n",
+			"list_add double add: new=%px, prev=%px, next=%px.\n",
 			new, prev, next))
 		return false;
 
@@ -43,16 +43,16 @@ bool __list_del_entry_valid(struct list_head *entry)
 	next = entry->next;
 
 	if (CHECK_DATA_CORRUPTION(next == LIST_POISON1,
-			"list_del corruption, %p->next is LIST_POISON1 (%p)\n",
+			"list_del corruption, %px->next is LIST_POISON1 (%px)\n",
 			entry, LIST_POISON1) ||
 	    CHECK_DATA_CORRUPTION(prev == LIST_POISON2,
-			"list_del corruption, %p->prev is LIST_POISON2 (%p)\n",
+			"list_del corruption, %px->prev is LIST_POISON2 (%px)\n",
 			entry, LIST_POISON2) ||
 	    CHECK_DATA_CORRUPTION(prev->next != entry,
-			"list_del corruption. prev->next should be %p, but was %p\n",
+			"list_del corruption. prev->next should be %px, but was %px\n",
 			entry, prev->next) ||
 	    CHECK_DATA_CORRUPTION(next->prev != entry,
-			"list_del corruption. next->prev should be %p, but was %p\n",
+			"list_del corruption. next->prev should be %px, but was %px\n",
 			entry, next->prev))
 		return false;