diff mbox series

[05/10] kasan: slab: always reset the tag in get_freepointer_safe()

Message ID 20210523004156.1-UnZ7NxI%akpm@linux-foundation.org (mailing list archive)
State New, archived
Headers show
Series [01/10] mm/shuffle: fix section mismatch warning | expand

Commit Message

Andrew Morton May 23, 2021, 12:41 a.m. UTC 
From: Alexander Potapenko <glider@google.com>
Subject: kasan: slab: always reset the tag in get_freepointer_safe()

With CONFIG_DEBUG_PAGEALLOC enabled, the kernel should also untag the
object pointer, as done in get_freepointer().

Failing to do so reportedly leads to SLUB freelist corruptions that
manifest as boot-time crashes.

Link: https://lkml.kernel.org/r/20210514072228.534418-1-glider@google.com
Signed-off-by: Alexander Potapenko <glider@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Elliot Berman <eberman@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/slub.c |    1 +
 1 file changed, 1 insertion(+)
diff mbox series

Patch

--- a/mm/slub.c~kasan-slab-always-reset-the-tag-in-get_freepointer_safe
+++ a/mm/slub.c
@@ -301,6 +301,7 @@  static inline void *get_freepointer_safe
 	if (!debug_pagealloc_enabled_static())
 		return get_freepointer(s, object);
 
+	object = kasan_reset_tag(object);
 	freepointer_addr = (unsigned long)object + s->offset;
 	copy_from_kernel_nofault(&p, (void **)freepointer_addr, sizeof(p));
 	return freelist_ptr(s, p, freepointer_addr);