Hi,
On 09/09/2012 06:01 PM, Francesco Lavra wrote:
>> +static int s5k4ecgx_load_firmware(struct v4l2_subdev *sd)
>> +{
>> + const struct firmware *fw;
>> + int err, i, regs_num;
>> + struct i2c_client *client = v4l2_get_subdevdata(sd);
>> + u16 val;
>> + u32 addr, crc, crc_file, addr_inc = 0;
>> +
>> + err = request_firmware(&fw, S5K4ECGX_FIRMWARE, sd->v4l2_dev->dev);
>> + if (err) {
>> + v4l2_err(sd, "Failed to read firmware %s\n", S5K4ECGX_FIRMWARE);
>> + return err;
>> + }
>> + regs_num = *(u32 *)(fw->data);
>> + v4l2_dbg(3, debug, sd, "FW: %s size %d register sets %d\n",
>> + S5K4ECGX_FIRMWARE, fw->size, regs_num);
>> + regs_num++; /* Add header */
>> + if (fw->size != regs_num * FW_RECORD_SIZE + FW_CRC_SIZE) {
>> + err = -EINVAL;
>> + goto fw_out;
>> + }
>> + crc_file = *(u32 *)(fw->data + regs_num * FW_RECORD_SIZE);
>
> Depending on the value of regs_num, this may result in unaligned access
Thanks for the catch. I think it is not the only place where unaligned
issues are possible. Since the data records are 4-byte address + 2-byte
value there is also an issue with reading the address entries. Assuming
fw->data is aligned to at least 2-bytes (not quite sure if we can assume
that) there should be no problem with reading 2-byte register values.
We could change the data types of the register values from u16 to u32,
wasting some memory (there is approximately 3 000 records), so there is
no other data types in the file structure than u32. Or use a patch as
below. Not sure what's better.
8<---------------------------------------------------------------------
>From a970480b99bdb74e2bf48e1a321724231e6516a0 Mon Sep 17 00:00:00 2001
From: Sylwester Nawrocki <sylvester.nawrocki@xxxxxxxxx>
Date: Sun, 9 Sep 2012 19:56:31 +0200
Subject: [PATCH] s5k4ecgx: Fix unaligned access issues
Signed-off-by: Sylwester Nawrocki <sylvester.nawrocki@xxxxxxxxx>
---
drivers/media/i2c/s5k4ecgx.c | 16 ++++++++++++----
1 files changed, 12 insertions(+), 4 deletions(-)
diff --git a/drivers/media/i2c/s5k4ecgx.c b/drivers/media/i2c/s5k4ecgx.c
index 0ef0b7d..4c6439a 100644
--- a/drivers/media/i2c/s5k4ecgx.c
+++ b/drivers/media/i2c/s5k4ecgx.c
@@ -24,6 +24,7 @@
#include <linux/module.h>
#include <linux/regulator/consumer.h>
#include <linux/slab.h>
+#include <asm/unaligned.h>
#include <media/media-entity.h>
#include <media/s5k4ecgx.h>
@@ -331,6 +332,7 @@ static int s5k4ecgx_load_firmware(struct v4l2_subdev *sd)
const struct firmware *fw;
int err, i, regs_num;
u32 addr, crc, crc_file, addr_inc = 0;
+ const u8 *ptr;
u16 val;
err = request_firmware(&fw, S5K4ECGX_FIRMWARE, sd->v4l2_dev->dev);
@@ -338,7 +340,7 @@ static int s5k4ecgx_load_firmware(struct v4l2_subdev *sd)
v4l2_err(sd, "Failed to read firmware %s\n", S5K4ECGX_FIRMWARE);
return err;
}
- regs_num = le32_to_cpu(*(u32 *)fw->data);
+ regs_num = le32_to_cpu(get_unaligned((__le32 *)fw->data));
v4l2_dbg(3, debug, sd, "FW: %s size %d register sets %d\n",
S5K4ECGX_FIRMWARE, fw->size, regs_num);
@@ -349,7 +351,8 @@ static int s5k4ecgx_load_firmware(struct v4l2_subdev *sd)
goto fw_out;
}
- crc_file = *(u32 *)(fw->data + regs_num * FW_RECORD_SIZE);
+ memcpy(&crc_file, fw->data + regs_num * FW_RECORD_SIZE, sizeof(u32));
+
crc = crc32_le(~0, fw->data, regs_num * FW_RECORD_SIZE);
if (crc != crc_file) {
v4l2_err(sd, "FW: invalid crc (%#x:%#x)\n", crc, crc_file);
@@ -357,9 +360,14 @@ static int s5k4ecgx_load_firmware(struct v4l2_subdev *sd)
goto fw_out;
}
+ ptr = fw->data + FW_RECORD_SIZE;
+
for (i = 1; i < regs_num; i++) {
- addr = le32_to_cpu(*(u32 *)(fw->data + i * FW_RECORD_SIZE));
- val = le16_to_cpu(*(u16 *)(fw->data + i * FW_RECORD_SIZE + 4));
+ addr = le32_to_cpu(get_unaligned((__le32 *)ptr));
+ ptr += 4;
+ val = le16_to_cpu(*(__le16 *)ptr);
+ ptr += FW_RECORD_SIZE;
+
if (addr - addr_inc != 2)
err = s5k4ecgx_write(client, addr, val);
else
--
1.7.2.5
8<----------------------------------------------------------------------------
--
Regards,
Sylwester
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