4.14-stable patches

added patches:
	slub-improve-bit-diffusion-for-freelist-ptr-obfuscation.patch

diff --git a/queue-4.14/series b/queue-4.14/series
index bb38f002887c112db84b06c7786e011a6493e4f9..e56718a36ea79f7340d89fde685fee0279b69d93 100644 (file)
--- a/queue-4.14/series
+++ b/queue-4.14/series
@@ -28,3 +28,4 @@ btrfs-remove-a-bug_on-from-merge_reloc_roots.patch
 btrfs-track-reloc-roots-based-on-their-commit-root-b.patch
 uapi-rename-ext2_swab-to-swab-and-share-globally-in-.patch
 misc-rtsx-set-correct-pcr_ops-for-rts522a.patch
+slub-improve-bit-diffusion-for-freelist-ptr-obfuscation.patch

diff --git a/queue-4.14/slub-improve-bit-diffusion-for-freelist-ptr-obfuscation.patch b/queue-4.14/slub-improve-bit-diffusion-for-freelist-ptr-obfuscation.patch
new file mode 100644 (file)
index 0000000..d232114
--- /dev/null
+++ b/queue-4.14/slub-improve-bit-diffusion-for-freelist-ptr-obfuscation.patch
@@ -0,0 +1,71 @@
+From 1ad53d9fa3f6168ebcf48a50e08b170432da2257 Mon Sep 17 00:00:00 2001
+From: Kees Cook <keescook@chromium.org>
+Date: Wed, 1 Apr 2020 21:04:23 -0700
+Subject: slub: improve bit diffusion for freelist ptr obfuscation
+
+From: Kees Cook <keescook@chromium.org>
+
+commit 1ad53d9fa3f6168ebcf48a50e08b170432da2257 upstream.
+
+Under CONFIG_SLAB_FREELIST_HARDENED=y, the obfuscation was relatively weak
+in that the ptr and ptr address were usually so close that the first XOR
+would result in an almost entirely 0-byte value[1], leaving most of the
+"secret" number ultimately being stored after the third XOR.  A single
+blind memory content exposure of the freelist was generally sufficient to
+learn the secret.
+
+Add a swab() call to mix bits a little more.  This is a cheap way (1
+cycle) to make attacks need more than a single exposure to learn the
+secret (or to know _where_ the exposure is in memory).
+
+kmalloc-32 freelist walk, before:
+
+ptr              ptr_addr            stored value      secret
+ffff90c22e019020@ffff90c22e019000 is 86528eb656b3b5bd (86528eb656b3b59d)
+ffff90c22e019040@ffff90c22e019020 is 86528eb656b3b5fd (86528eb656b3b59d)
+ffff90c22e019060@ffff90c22e019040 is 86528eb656b3b5bd (86528eb656b3b59d)
+ffff90c22e019080@ffff90c22e019060 is 86528eb656b3b57d (86528eb656b3b59d)
+ffff90c22e0190a0@ffff90c22e019080 is 86528eb656b3b5bd (86528eb656b3b59d)
+...
+
+after:
+
+ptr              ptr_addr            stored value      secret
+ffff9eed6e019020@ffff9eed6e019000 is 793d1135d52cda42 (86528eb656b3b59d)
+ffff9eed6e019040@ffff9eed6e019020 is 593d1135d52cda22 (86528eb656b3b59d)
+ffff9eed6e019060@ffff9eed6e019040 is 393d1135d52cda02 (86528eb656b3b59d)
+ffff9eed6e019080@ffff9eed6e019060 is 193d1135d52cdae2 (86528eb656b3b59d)
+ffff9eed6e0190a0@ffff9eed6e019080 is f93d1135d52cdac2 (86528eb656b3b59d)
+
+[1] https://blog.infosectcbr.com.au/2020/03/weaknesses-in-linux-kernel-heap.html
+
+Fixes: 2482ddec670f ("mm: add SLUB free list pointer obfuscation")
+Reported-by: Silvio Cesare <silvio.cesare@gmail.com>
+Signed-off-by: Kees Cook <keescook@chromium.org>
+Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
+Cc: Christoph Lameter <cl@linux.com>
+Cc: Pekka Enberg <penberg@kernel.org>
+Cc: David Rientjes <rientjes@google.com>
+Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
+Cc: <stable@vger.kernel.org>
+Link: http://lkml.kernel.org/r/202003051623.AF4F8CB@keescook
+Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
+[kees: Backport to v4.19 which doesn't call kasan_reset_untag()]
+Signed-off-by: Kees Cook <keescook@chromium.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ mm/slub.c |    2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+--- a/mm/slub.c
++++ b/mm/slub.c
+@@ -248,7 +248,7 @@ static inline void *freelist_ptr(const s
+                                unsigned long ptr_addr)
+ {
+ #ifdef CONFIG_SLAB_FREELIST_HARDENED
+-      return (void *)((unsigned long)ptr ^ s->random ^ ptr_addr);
++      return (void *)((unsigned long)ptr ^ s->random ^ swab(ptr_addr));
+ #else
+       return ptr;
+ #endif