[merged mm-hotfixes-stable] kasan-fix-type-cast-in-memory_is_poisoned_n.patch removed from -mm tree

[merged mm-hotfixes-stable] kasan-fix-type-cast-in-memory_is_poisoned_n.patch removed from -mm tree

[Andrew Morton]

The quilt patch titled
     Subject: kasan: fix type cast in memory_is_poisoned_n
has been removed from the -mm tree.  Its filename was
     kasan-fix-type-cast-in-memory_is_poisoned_n.patch

This patch was dropped because it was merged into the mm-hotfixes-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------
From: Andrey Konovalov <andreyknvl@google.com>
Subject: kasan: fix type cast in memory_is_poisoned_n
Date: Tue, 4 Jul 2023 02:52:05 +0200

Commit bb6e04a173f0 ("kasan: use internal prototypes matching gcc-13
builtins") introduced a bug into the memory_is_poisoned_n implementation:
it effectively removed the cast to a signed integer type after applying
KASAN_GRANULE_MASK.

As a result, KASAN started failing to properly check memset, memcpy, and
other similar functions.

Fix the bug by adding the cast back (through an additional signed integer
variable to make the code more readable).

Link: https://lkml.kernel.org/r/8c9e0251c2b8b81016255709d4ec42942dcaf018.1688431866.git.andreyknvl@google.com
Fixes: bb6e04a173f0 ("kasan: use internal prototypes matching gcc-13 builtins")
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Marco Elver <elver@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/kasan/generic.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/mm/kasan/generic.c~kasan-fix-type-cast-in-memory_is_poisoned_n
+++ a/mm/kasan/generic.c
@@ -130,9 +130,10 @@ static __always_inline bool memory_is_po
 	if (unlikely(ret)) {
 		const void *last_byte = addr + size - 1;
 		s8 *last_shadow = (s8 *)kasan_mem_to_shadow(last_byte);
+		s8 last_accessible_byte = (unsigned long)last_byte & KASAN_GRANULE_MASK;
 
 		if (unlikely(ret != (unsigned long)last_shadow ||
-			(((long)last_byte & KASAN_GRANULE_MASK) >= *last_shadow)))
+			     last_accessible_byte >= *last_shadow))
 			return true;
 	}
 	return false;
_

Patches currently in -mm which might be from andreyknvl@google.com are