linux-kernel - [PATCH] x86/csum: Add KASAN/KCSAN instrumentation

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Message-Id: <20220126171232.2599547-1-jannh@google.com>
Date:   Wed, 26 Jan 2022 18:12:32 +0100
From:   Jann Horn <jannh@...gle.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org
Cc:     "H. Peter Anvin" <hpa@...or.com>, linux-kernel@...r.kernel.org,
        Andrey Ryabinin <ryabinin.a.a@...il.com>,
        Alexander Potapenko <glider@...gle.com>,
        Andrey Konovalov <andreyknvl@...il.com>,
        Dmitry Vyukov <dvyukov@...gle.com>, kasan-dev@...glegroups.com,
        Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH] x86/csum: Add KASAN/KCSAN instrumentation

In the optimized X86 version of the copy-with-checksum helpers, use
instrument_*() before accessing buffers from assembly code so that KASAN
and KCSAN don't have blind spots there.

Signed-off-by: Jann Horn <jannh@...gle.com>
---
 arch/x86/lib/csum-partial_64.c  | 3 +++
 arch/x86/lib/csum-wrappers_64.c | 9 +++++++++
 2 files changed, 12 insertions(+)

diff --git a/arch/x86/lib/csum-partial_64.c b/arch/x86/lib/csum-partial_64.c
index 1f8a8f895173..8b0c353cd212 100644
--- a/arch/x86/lib/csum-partial_64.c
+++ b/arch/x86/lib/csum-partial_64.c
@@ -8,6 +8,7 @@
  
 #include <linux/compiler.h>
 #include <linux/export.h>
+#include <linux/instrumented.h>
 #include <asm/checksum.h>
 #include <asm/word-at-a-time.h>
 
@@ -37,6 +38,8 @@ __wsum csum_partial(const void *buff, int len, __wsum sum)
 	u64 temp64 = (__force u64)sum;
 	unsigned odd, result;
 
+	instrument_read(buff, len);
+
 	odd = 1 & (unsigned long) buff;
 	if (unlikely(odd)) {
 		if (unlikely(len == 0))
diff --git a/arch/x86/lib/csum-wrappers_64.c b/arch/x86/lib/csum-wrappers_64.c
index 189344924a2b..087f3c4cb89f 100644
--- a/arch/x86/lib/csum-wrappers_64.c
+++ b/arch/x86/lib/csum-wrappers_64.c
@@ -6,6 +6,8 @@
  */
 #include <asm/checksum.h>
 #include <linux/export.h>
+#include <linux/in6.h>
+#include <linux/instrumented.h>
 #include <linux/uaccess.h>
 #include <asm/smap.h>
 
@@ -26,6 +28,7 @@ csum_and_copy_from_user(const void __user *src, void *dst, int len)
 	__wsum sum;
 
 	might_sleep();
+	instrument_write(dst, len);
 	if (!user_access_begin(src, len))
 		return 0;
 	sum = csum_partial_copy_generic((__force const void *)src, dst, len);
@@ -51,6 +54,7 @@ csum_and_copy_to_user(const void *src, void __user *dst, int len)
 	__wsum sum;
 
 	might_sleep();
+	instrument_read(src, len);
 	if (!user_access_begin(dst, len))
 		return 0;
 	sum = csum_partial_copy_generic(src, (void __force *)dst, len);
@@ -71,6 +75,8 @@ EXPORT_SYMBOL(csum_and_copy_to_user);
 __wsum
 csum_partial_copy_nocheck(const void *src, void *dst, int len)
 {
+	instrument_write(dst, len);
+	instrument_read(src, len);
 	return csum_partial_copy_generic(src, dst, len);
 }
 EXPORT_SYMBOL(csum_partial_copy_nocheck);
@@ -81,6 +87,9 @@ __sum16 csum_ipv6_magic(const struct in6_addr *saddr,
 {
 	__u64 rest, sum64;
 
+	instrument_read(saddr, sizeof(*saddr));
+	instrument_read(daddr, sizeof(*daddr));
+
 	rest = (__force __u64)htonl(len) + (__force __u64)htons(proto) +
 		(__force __u64)sum;
 

base-commit: 0280e3c58f92b2fe0e8fbbdf8d386449168de4a8
-- 
2.35.0.rc0.227.g00780c9af4-goog