From: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Subject: kasan, slab: fix conflicts with CONFIG_HARDENED_USERCOPY
Similarly to 96fedce2 ("kasan: make tag based mode work with
CONFIG_HARDENED_USERCOPY"), we need to reset pointer tags in
__check_heap_object() in mm/slab.c before doing any pointer math.
Link: http://lkml.kernel.org/r/9a5c0f958db10e69df5ff9f2b997866b56b7effc.1550602886.git.andreyknvl@xxxxxxxxxx
Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Tested-by: Qian Cai <cai@xxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Evgeniy Stepanov <eugenis@xxxxxxxxxx>
Cc: Kostya Serebryany <kcc@xxxxxxxxxx>
Cc: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
--- a/mm/slab.c~kasan-slab-fix-conflicts-with-config_hardened_usercopy
+++ a/mm/slab.c
@@ -4408,6 +4408,8 @@ void __check_heap_object(const void *ptr
unsigned int objnr;
unsigned long offset;
+ ptr = kasan_reset_tag(ptr);
+
/* Find and validate object. */
cachep = page->slab_cache;
objnr = obj_to_index(cachep, page, (void *)ptr);
_
