linux-kernel - [PATCH 7/8] misc: eeprom: at25: move eeprom boundary checks to mem_read/mem

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Date:	Mon, 27 Jul 2015 00:18:52 +0300
From:	Vladimir Zapolskiy <vz@...ia.com>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	linux-kernel@...r.kernel.org
Subject: [PATCH 7/8] misc: eeprom: at25: move eeprom boundary checks to mem_read/mem_write

The sanity checks for overflow over eeprom size are not needed, if
eeprom is accessed from userspace over sysfs interface, because this
is handled by fs/sysfs/file.c, however in case of reading or writing
within the kernel it might be still reasonable to pass the check.

The change moves these checks from shared at25_ee_read() and
at25_ee_write() directly to at25_mem_read() and at25_mem_write(), no
functional change.

Signed-off-by: Vladimir Zapolskiy <vz@...ia.com>
---
 drivers/misc/eeprom/at25.c | 28 ++++++++++++++--------------
 1 file changed, 14 insertions(+), 14 deletions(-)

diff --git a/drivers/misc/eeprom/at25.c b/drivers/misc/eeprom/at25.c
index 0a1af93..c4f5c4a 100644
--- a/drivers/misc/eeprom/at25.c
+++ b/drivers/misc/eeprom/at25.c
@@ -77,13 +77,6 @@ at25_ee_read(
 	struct spi_message	m;
 	u8			instr;
 
-	if (unlikely(offset >= at25->bin.size))
-		return 0;
-	if ((offset + count) > at25->bin.size)
-		count = at25->bin.size - offset;
-	if (unlikely(!count))
-		return count;
-
 	cp = command;
 
 	instr = AT25_READ;
@@ -155,13 +148,6 @@ at25_ee_write(struct at25_data *at25, const char *buf, loff_t off,
 	unsigned		buf_size;
 	u8			*bounce;
 
-	if (unlikely(off >= at25->bin.size))
-		return -EFBIG;
-	if ((off + count) > at25->bin.size)
-		count = at25->bin.size - off;
-	if (unlikely(!count))
-		return count;
-
 	/* Temp buffer starts with command and address */
 	buf_size = at25->chip.page_size;
 	if (buf_size > io_limit)
@@ -288,6 +274,13 @@ static ssize_t at25_mem_read(struct memory_accessor *mem, char *buf,
 {
 	struct at25_data *at25 = container_of(mem, struct at25_data, mem);
 
+	if (unlikely(offset >= at25->bin.size))
+		return 0;
+	if ((offset + count) > at25->bin.size)
+		count = at25->bin.size - offset;
+	if (unlikely(!count))
+		return count;
+
 	return at25_ee_read(at25, buf, offset, count);
 }
 
@@ -296,7 +289,13 @@ static ssize_t at25_mem_write(struct memory_accessor *mem, const char *buf,
 {
 	struct at25_data *at25 = container_of(mem, struct at25_data, mem);
 
+	if (unlikely(offset >= at25->bin.size))
+		return -EFBIG;
+	if ((offset + count) > at25->bin.size)
+		count = at25->bin.size - offset;
+	if (unlikely(!count))
+		return count;
+
 	return at25_ee_write(at25, buf, offset, count);
 }
 
-- 
2.1.4

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