This is a note to let you know that I've just added the patch titled
kcsan: Instrument memcpy/memset/memmove with newer Clang
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kcsan-instrument-memcpy-memset-memmove-with-newer-clang.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 7c201739beef1a586d806463f1465429cdce34c5 Mon Sep 17 00:00:00 2001
From: Marco Elver <elver@xxxxxxxxxx>
Date: Mon, 12 Sep 2022 11:45:40 +0200
Subject: kcsan: Instrument memcpy/memset/memmove with newer Clang
From: Marco Elver <elver@xxxxxxxxxx>
commit 7c201739beef1a586d806463f1465429cdce34c5 upstream.
With Clang version 16+, -fsanitize=thread will turn
memcpy/memset/memmove calls in instrumented functions into
__tsan_memcpy/__tsan_memset/__tsan_memmove calls respectively.
Add these functions to the core KCSAN runtime, so that we (a) catch data
races with mem* functions, and (b) won't run into linker errors with
such newer compilers.
Cc: stable@xxxxxxxxxxxxxxx # v5.10+
Signed-off-by: Marco Elver <elver@xxxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/kcsan/core.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 50 insertions(+)
--- a/kernel/kcsan/core.c
+++ b/kernel/kcsan/core.c
@@ -9,10 +9,12 @@
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/list.h>
+#include <linux/minmax.h>
#include <linux/moduleparam.h>
#include <linux/percpu.h>
#include <linux/preempt.h>
#include <linux/sched.h>
+#include <linux/string.h>
#include <linux/uaccess.h>
#include "atomic.h"
@@ -1045,3 +1047,51 @@ EXPORT_SYMBOL(__tsan_atomic_thread_fence
void __tsan_atomic_signal_fence(int memorder);
void __tsan_atomic_signal_fence(int memorder) { }
EXPORT_SYMBOL(__tsan_atomic_signal_fence);
+
+#ifdef __HAVE_ARCH_MEMSET
+void *__tsan_memset(void *s, int c, size_t count);
+noinline void *__tsan_memset(void *s, int c, size_t count)
+{
+ /*
+ * Instead of not setting up watchpoints where accessed size is greater
+ * than MAX_ENCODABLE_SIZE, truncate checked size to MAX_ENCODABLE_SIZE.
+ */
+ size_t check_len = min_t(size_t, count, MAX_ENCODABLE_SIZE);
+
+ check_access(s, check_len, KCSAN_ACCESS_WRITE, _RET_IP_);
+ return memset(s, c, count);
+}
+#else
+void *__tsan_memset(void *s, int c, size_t count) __alias(memset);
+#endif
+EXPORT_SYMBOL(__tsan_memset);
+
+#ifdef __HAVE_ARCH_MEMMOVE
+void *__tsan_memmove(void *dst, const void *src, size_t len);
+noinline void *__tsan_memmove(void *dst, const void *src, size_t len)
+{
+ size_t check_len = min_t(size_t, len, MAX_ENCODABLE_SIZE);
+
+ check_access(dst, check_len, KCSAN_ACCESS_WRITE, _RET_IP_);
+ check_access(src, check_len, 0, _RET_IP_);
+ return memmove(dst, src, len);
+}
+#else
+void *__tsan_memmove(void *dst, const void *src, size_t len) __alias(memmove);
+#endif
+EXPORT_SYMBOL(__tsan_memmove);
+
+#ifdef __HAVE_ARCH_MEMCPY
+void *__tsan_memcpy(void *dst, const void *src, size_t len);
+noinline void *__tsan_memcpy(void *dst, const void *src, size_t len)
+{
+ size_t check_len = min_t(size_t, len, MAX_ENCODABLE_SIZE);
+
+ check_access(dst, check_len, KCSAN_ACCESS_WRITE, _RET_IP_);
+ check_access(src, check_len, 0, _RET_IP_);
+ return memcpy(dst, src, len);
+}
+#else
+void *__tsan_memcpy(void *dst, const void *src, size_t len) __alias(memcpy);
+#endif
+EXPORT_SYMBOL(__tsan_memcpy);
Patches currently in stable-queue which might be from elver@xxxxxxxxxx are
queue-5.10/objtool-kcsan-add-volatile-read-write-instrumentatio.patch
queue-5.10/kcsan-instrument-memcpy-memset-memmove-with-newer-clang.patch
queue-5.10/net-switch-to-storing-kcov-handle-directly-in-sk_buf.patch
