[PATCH 2/4] kasan, slab: fix conflicts with CONFIG_HARDENED_USERCOPY

[Andrey Konovalov]

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.

Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
---
 mm/slab.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/mm/slab.c b/mm/slab.c
index 78eb8c5bf4e4..c84458281a88 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -4408,6 +4408,8 @@ void __check_heap_object(const void *ptr, unsigned long n, struct page *page,
 	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);
-- 
2.21.0.rc0.258.g878e2cd30e-goog