[PATCH AUTOSEL 5.6 188/606] kasan: disable branch tracing for core runtime

[PATCH AUTOSEL 5.6 188/606] kasan: disable branch tracing for core runtime

[Sasha Levin]

From: Marco Elver <elver@google.com>

commit 33cd65e73abd693c00c4156cf23677c453b41b3b upstream.

During early boot, while KASAN is not yet initialized, it is possible to
enter reporting code-path and end up in kasan_report().

While uninitialized, the branch there prevents generating any reports,
however, under certain circumstances when branches are being traced
(TRACE_BRANCH_PROFILING), we may recurse deep enough to cause kernel
reboots without warning.

To prevent similar issues in future, we should disable branch tracing
for the core runtime.

[elver@google.com: remove duplicate DISABLE_BRANCH_PROFILING, per Qian Cai]
  Link: https://lore.kernel.org/lkml/20200517011732.GE24705@shao2-debian/
  Link: http://lkml.kernel.org/r/20200522075207.157349-1-elver@google.com
Reported-by: kernel test robot <rong.a.chen@intel.com>
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrey Konovalov <andreyknvl@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Qian Cai <cai@lca.pw>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r//20200517011732.GE24705@shao2-debian/
Link: http://lkml.kernel.org/r/20200519182459.87166-1-elver@google.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 mm/kasan/Makefile  | 8 ++++----
 mm/kasan/generic.c | 1 -
 mm/kasan/tags.c    | 1 -
 3 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/mm/kasan/Makefile b/mm/kasan/Makefile
index 08b43de2383b..f36ffc090f5f 100644
--- a/mm/kasan/Makefile
+++ b/mm/kasan/Makefile
@@ -14,10 +14,10 @@ CFLAGS_REMOVE_tags.o = $(CC_FLAGS_FTRACE)
 # Function splitter causes unnecessary splits in __asan_load1/__asan_store1
 # see: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63533
 
-CFLAGS_common.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector)
-CFLAGS_generic.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector)
-CFLAGS_generic_report.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector)
-CFLAGS_tags.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector)
+CFLAGS_common.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -DDISABLE_BRANCH_PROFILING
+CFLAGS_generic.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -DDISABLE_BRANCH_PROFILING
+CFLAGS_generic_report.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -DDISABLE_BRANCH_PROFILING
+CFLAGS_tags.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector) -DDISABLE_BRANCH_PROFILING
 
 obj-$(CONFIG_KASAN) := common.o init.o report.o
 obj-$(CONFIG_KASAN_GENERIC) += generic.o generic_report.o quarantine.o
diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c
index 616f9dd82d12..76a80033e0b7 100644
--- a/mm/kasan/generic.c
+++ b/mm/kasan/generic.c
@@ -15,7 +15,6 @@
  */
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
-#define DISABLE_BRANCH_PROFILING
 
 #include <linux/export.h>
 #include <linux/interrupt.h>
diff --git a/mm/kasan/tags.c b/mm/kasan/tags.c
index 0e987c9ca052..caf4efd9888c 100644
--- a/mm/kasan/tags.c
+++ b/mm/kasan/tags.c
@@ -12,7 +12,6 @@
  */
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
-#define DISABLE_BRANCH_PROFILING
 
 #include <linux/export.h>
 #include <linux/interrupt.h>
-- 
2.25.1

[PATCH AUTOSEL 5.6 192/606] z3fold: fix use-after-free when freeing handles

[Sasha Levin]

From: Uladzislau Rezki <uladzislau.rezki@sony.com>

commit d8f117abb380ba968b5e3ef2042d901c02872a4c upstream.

free_handle() for a foreign handle may race with inter-page compaction,
what can lead to memory corruption.

To avoid that, take write lock not read lock in free_handle to be
synchronized with __release_z3fold_page().

For example KASAN can detect it:

  ==================================================================
  BUG: KASAN: use-after-free in LZ4_decompress_safe+0x2c4/0x3b8
  Read of size 1 at addr ffffffc976695ca3 by task GoogleApiHandle/4121

  CPU: 0 PID: 4121 Comm: GoogleApiHandle Tainted: P S         OE     4.19.81-perf+ #162
  Hardware name: Sony Mobile Communications. PDX-203(KONA) (DT)
  Call trace:
     LZ4_decompress_safe+0x2c4/0x3b8
     lz4_decompress_crypto+0x3c/0x70
     crypto_decompress+0x58/0x70
     zcomp_decompress+0xd4/0x120
     ...

Apart from that, initialize zhdr->mapped_count in init_z3fold_page() and
remove "newpage" variable because it is not used anywhere.

Signed-off-by: Uladzislau Rezki <uladzislau.rezki@sony.com>
Signed-off-by: Vitaly Wool <vitaly.wool@konsulko.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Qian Cai <cai@lca.pw>
Cc: Raymond Jennings <shentino@gmail.com>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20200520082100.28876-1-vitaly.wool@konsulko.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 mm/z3fold.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/mm/z3fold.c b/mm/z3fold.c
index 42f31c4b53ad..8c3bb5e508b8 100644
--- a/mm/z3fold.c
+++ b/mm/z3fold.c
@@ -318,16 +318,16 @@ static inline void free_handle(unsigned long handle)
 	slots = handle_to_slots(handle);
 	write_lock(&slots->lock);
 	*(unsigned long *)handle = 0;
-	write_unlock(&slots->lock);
-	if (zhdr->slots == slots)
+	if (zhdr->slots == slots) {
+		write_unlock(&slots->lock);
 		return; /* simple case, nothing else to do */
+	}
 
 	/* we are freeing a foreign handle if we are here */
 	zhdr->foreign_handles--;
 	is_free = true;
-	read_lock(&slots->lock);
 	if (!test_bit(HANDLES_ORPHANED, &slots->pool)) {
-		read_unlock(&slots->lock);
+		write_unlock(&slots->lock);
 		return;
 	}
 	for (i = 0; i <= BUDDY_MASK; i++) {
@@ -336,7 +336,7 @@ static inline void free_handle(unsigned long handle)
 			break;
 		}
 	}
-	read_unlock(&slots->lock);
+	write_unlock(&slots->lock);
 
 	if (is_free) {
 		struct z3fold_pool *pool = slots_to_pool(slots);
@@ -422,6 +422,7 @@ static struct z3fold_header *init_z3fold_page(struct page *page, bool headless,
 	zhdr->start_middle = 0;
 	zhdr->cpu = -1;
 	zhdr->foreign_handles = 0;
+	zhdr->mapped_count = 0;
 	zhdr->slots = slots;
 	zhdr->pool = pool;
 	INIT_LIST_HEAD(&zhdr->buddy);
-- 
2.25.1