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Date:   Sun, 31 May 2020 11:53:00 +0200
From:   Jens Thoms Toerring <jt@...rring.de>
To:     Mark Brown <broonie@...nel.org>
Cc:     linux-kernel@...r.kernel.org
Subject: [PATCH v4] regmap: fix alignment issue

The assembly and disassembly of data to be sent to or received from
a device invoke functions regmap_format_XX() and regmap_parse_XX()
that extract or insert data items from or into a buffer, using
assignments. In some cases the functions are called with a buffer
pointer with an odd address. On architectures with strict alignment
requirements this can result in a kernel crash. The assignments
have been replaced by functions that take alignment into account.

Signed-off-by: Jens Thoms Toerring <jt@...rring.de>
---
 drivers/base/regmap/regmap.c | 104 ++++++++++++++++++++-----------------------
 1 file changed, 48 insertions(+), 56 deletions(-)

diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index c472f62..4cde237 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -17,6 +17,7 @@
 #include <linux/delay.h>
 #include <linux/log2.h>
 #include <linux/hwspinlock.h>
+#include <asm/unaligned.h>
 
 #define CREATE_TRACE_POINTS
 #include "trace.h"
@@ -249,22 +250,20 @@ static void regmap_format_8(void *buf, unsigned int val, unsigned int shift)
 
 static void regmap_format_16_be(void *buf, unsigned int val, unsigned int shift)
 {
-	__be16 *b = buf;
-
-	b[0] = cpu_to_be16(val << shift);
+	put_unaligned_be16(val << shift, buf);
 }
 
 static void regmap_format_16_le(void *buf, unsigned int val, unsigned int shift)
 {
-	__le16 *b = buf;
-
-	b[0] = cpu_to_le16(val << shift);
+	put_unaligned_le16(val << shift, buf);
 }
 
 static void regmap_format_16_native(void *buf, unsigned int val,
 				    unsigned int shift)
 {
-	*(u16 *)buf = val << shift;
+	u16 v = val << shift;
+
+	memcpy(buf, &v, sizeof(v));
 }
 
 static void regmap_format_24(void *buf, unsigned int val, unsigned int shift)
@@ -280,43 +279,39 @@ static void regmap_format_24(void *buf, unsigned int val, unsigned int shift)
 
 static void regmap_format_32_be(void *buf, unsigned int val, unsigned int shift)
 {
-	__be32 *b = buf;
-
-	b[0] = cpu_to_be32(val << shift);
+	put_unaligned_be32(val << shift, buf);
 }
 
 static void regmap_format_32_le(void *buf, unsigned int val, unsigned int shift)
 {
-	__le32 *b = buf;
-
-	b[0] = cpu_to_le32(val << shift);
+	put_unaligned_le32(val << shift, buf);
 }
 
 static void regmap_format_32_native(void *buf, unsigned int val,
 				    unsigned int shift)
 {
-	*(u32 *)buf = val << shift;
+	u32 v = val << shift;
+
+	memcpy(buf, &v, sizeof(v));
 }
 
 #ifdef CONFIG_64BIT
 static void regmap_format_64_be(void *buf, unsigned int val, unsigned int shift)
 {
-	__be64 *b = buf;
-
-	b[0] = cpu_to_be64((u64)val << shift);
+	put_unaligned_be64((u64) val << shift, buf);
 }
 
 static void regmap_format_64_le(void *buf, unsigned int val, unsigned int shift)
 {
-	__le64 *b = buf;
-
-	b[0] = cpu_to_le64((u64)val << shift);
+	put_unaligned_le64((u64) val << shift, buf);
 }
 
 static void regmap_format_64_native(void *buf, unsigned int val,
 				    unsigned int shift)
 {
-	*(u64 *)buf = (u64)val << shift;
+	u64 v = (u64) val << shift;
+
+	memcpy(buf, &v, sizeof(v));
 }
 #endif
 
@@ -333,35 +328,34 @@ static unsigned int regmap_parse_8(const void *buf)
 
 static unsigned int regmap_parse_16_be(const void *buf)
 {
-	const __be16 *b = buf;
-
-	return be16_to_cpu(b[0]);
+	return get_unaligned_be16(buf);
 }
 
 static unsigned int regmap_parse_16_le(const void *buf)
 {
-	const __le16 *b = buf;
-
-	return le16_to_cpu(b[0]);
+	return get_unaligned_le16(buf);
 }
 
 static void regmap_parse_16_be_inplace(void *buf)
 {
-	__be16 *b = buf;
-
-	b[0] = be16_to_cpu(b[0]);
+	u16 v = get_unaligned_be16(buf);
+
+	memcpy(buf, &v, sizeof(v));
 }
 
 static void regmap_parse_16_le_inplace(void *buf)
 {
-	__le16 *b = buf;
-
-	b[0] = le16_to_cpu(b[0]);
+	u16 v = get_unaligned_le16(buf);
+
+	memcpy(buf, &v, sizeof(v));
 }
 
 static unsigned int regmap_parse_16_native(const void *buf)
 {
-	return *(u16 *)buf;
+	u16 v;
+
+	memcpy(&v, buf, sizeof(v));
+	return v;
 }
 
 static unsigned int regmap_parse_24(const void *buf)
@@ -376,69 +370,67 @@ static unsigned int regmap_parse_24(const void *buf)
 
 static unsigned int regmap_parse_32_be(const void *buf)
 {
-	const __be32 *b = buf;
-
-	return be32_to_cpu(b[0]);
+	return get_unaligned_be32(buf);
 }
 
 static unsigned int regmap_parse_32_le(const void *buf)
 {
-	const __le32 *b = buf;
-
-	return le32_to_cpu(b[0]);
+	return get_unaligned_le32(buf);
 }
 
 static void regmap_parse_32_be_inplace(void *buf)
 {
-	__be32 *b = buf;
+	u32 v = get_unaligned_be32(buf);
 
-	b[0] = be32_to_cpu(b[0]);
+	memcpy(buf, &v, sizeof(v));
 }
 
 static void regmap_parse_32_le_inplace(void *buf)
 {
-	__le32 *b = buf;
+	u32 v = get_unaligned_le32(buf);
 
-	b[0] = le32_to_cpu(b[0]);
+	memcpy(buf, &v, sizeof(v));
 }
 
 static unsigned int regmap_parse_32_native(const void *buf)
 {
-	return *(u32 *)buf;
+	u32 v;
+
+	memcpy(&v, buf, sizeof(v));
+	return v;
 }
 
 #ifdef CONFIG_64BIT
 static unsigned int regmap_parse_64_be(const void *buf)
 {
-	const __be64 *b = buf;
-
-	return be64_to_cpu(b[0]);
+	return get_unaligned_be64(buf);
 }
 
 static unsigned int regmap_parse_64_le(const void *buf)
 {
-	const __le64 *b = buf;
-
-	return le64_to_cpu(b[0]);
+	return get_unaligned_le64(buf);
 }
 
 static void regmap_parse_64_be_inplace(void *buf)
 {
-	__be64 *b = buf;
+	u64 v =  get_unaligned_be64(buf);
 
-	b[0] = be64_to_cpu(b[0]);
+	memcpy(buf, &v, sizeof(v));
 }
 
 static void regmap_parse_64_le_inplace(void *buf)
 {
-	__le64 *b = buf;
+	u64 v = get_unaligned_le64(buf);
 
-	b[0] = le64_to_cpu(b[0]);
+	memcpy(buf, &v, sizeof(v));
 }
 
 static unsigned int regmap_parse_64_native(const void *buf)
 {
-	return *(u64 *)buf;
+	u64 v;
+
+	memcpy(&v, buf, sizeof(v));
+	return v;
 }
 #endif
 
-- 
1.9.1

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