> -----Original Message----- > From: Jonathan Cameron [mailto:[email protected]] > Sent: 09 April, 2015 14:51 > To: Tirdea, Irina; [email protected]; Hartmut Knaack > Cc: [email protected] > Subject: Re: [PATCH 7/8] iio: accel: mma9551_core: prevent buffer overrun > > On 08/04/15 15:37, Irina Tirdea wrote: > > The mma9551 functions that read/write word arrays from the > > device have a limit for the buffer size given by the device > > specifications. > > > > Check that the requested buffer length is within required limits > > when transferring word arrays. This will prevent buffer overrun > > in the mma9551_read/write_*_words functions and also in the > > mma9551_transfer call when writing into the MBOX response/request > > structure. > > > > Change the prototype for the mma9551_read/write_*_words functions > > to receive the length of the buffer in words (instead of bytes) since > > we are using a word buffer. This will prevent users from sending an > > odd number of bytes for a word array. > > > > Signed-off-by: Irina Tirdea <[email protected]> > > Suggested-by: Hartmut Knaack <[email protected]> > This is a bit of a mixture of a fix and a refactor. That leaves > us with a rather longer fix patch than would be ideal. > > could you break this into the minimal fix (just check limits and perhaps > fix the buffer length to be half as long) then a follow up rework patch > that gets you to the state at the end of this current patch? > Sure, I'll break this in two patches: the actual fix and the change in function signature. > Thanks, > > J > > --- > > drivers/iio/accel/mma9551_core.c | 45 > > ++++++++++++++++++++++++++-------------- > > drivers/iio/accel/mma9553.c | 7 ++++--- > > 2 files changed, 34 insertions(+), 18 deletions(-) > > > > diff --git a/drivers/iio/accel/mma9551_core.c > > b/drivers/iio/accel/mma9551_core.c > > index 438cfed..5c6f69d 100644 > > --- a/drivers/iio/accel/mma9551_core.c > > +++ b/drivers/iio/accel/mma9551_core.c > > @@ -373,7 +373,7 @@ EXPORT_SYMBOL(mma9551_read_status_word); > > * @client: I2C client > > * @app_id: Application ID > > * @reg: Application register > > - * @len: Length of array to read in bytes > > + * @len: Length of array to read (in words) > > * @buf: Array of words to read > > * > > * Read multiple configuration registers (word-sized registers). > > @@ -388,15 +388,20 @@ int mma9551_read_config_words(struct i2c_client > > *client, u8 app_id, > > u16 reg, u8 len, u16 *buf) > > { > > int ret; > > - u8 i, len_words = len / sizeof(u16); > > - __be16 be_buf[MMA9551_MAX_MAILBOX_DATA_REGS]; > > + u8 i; > > + __be16 be_buf[MMA9551_MAX_MAILBOX_DATA_REGS / 2]; > > + > > + if (len > ARRAY_SIZE(be_buf)) { > > + dev_err(&client->dev, "Invalid buffer size %d\n", len); > > + return -EINVAL; > > + } > > > > ret = mma9551_transfer(client, app_id, MMA9551_CMD_READ_CONFIG, > > - reg, NULL, 0, (u8 *) be_buf, len); > > + reg, NULL, 0, (u8 *)be_buf, len * sizeof(u16)); > > if (ret < 0) > > return ret; > > > > - for (i = 0; i < len_words; i++) > > + for (i = 0; i < len; i++) > > buf[i] = be16_to_cpu(be_buf[i]); > > > > return 0; > > @@ -408,7 +413,7 @@ EXPORT_SYMBOL(mma9551_read_config_words); > > * @client: I2C client > > * @app_id: Application ID > > * @reg: Application register > > - * @len: Length of array to read in bytes > > + * @len: Length of array to read (in words) > > * @buf: Array of words to read > > * > > * Read multiple status registers (word-sized registers). > > @@ -423,15 +428,20 @@ int mma9551_read_status_words(struct i2c_client > > *client, u8 app_id, > > u16 reg, u8 len, u16 *buf) > > { > > int ret; > > - u8 i, len_words = len / sizeof(u16); > > - __be16 be_buf[MMA9551_MAX_MAILBOX_DATA_REGS]; > > + u8 i; > > + __be16 be_buf[MMA9551_MAX_MAILBOX_DATA_REGS / 2]; > > + > > + if (len > ARRAY_SIZE(be_buf)) { > > + dev_err(&client->dev, "Invalid buffer size %d\n", len); > > + return -EINVAL; > > + } > > > > ret = mma9551_transfer(client, app_id, MMA9551_CMD_READ_STATUS, > > - reg, NULL, 0, (u8 *) be_buf, len); > > + reg, NULL, 0, (u8 *)be_buf, len * sizeof(u16)); > > if (ret < 0) > > return ret; > > > > - for (i = 0; i < len_words; i++) > > + for (i = 0; i < len; i++) > > buf[i] = be16_to_cpu(be_buf[i]); > > > > return 0; > > @@ -443,7 +453,7 @@ EXPORT_SYMBOL(mma9551_read_status_words); > > * @client: I2C client > > * @app_id: Application ID > > * @reg: Application register > > - * @len: Length of array to write in bytes > > + * @len: Length of array to write (in words) > > * @buf: Array of words to write > > * > > * Write multiple configuration registers (word-sized registers). > > @@ -457,14 +467,19 @@ EXPORT_SYMBOL(mma9551_read_status_words); > > int mma9551_write_config_words(struct i2c_client *client, u8 app_id, > > u16 reg, u8 len, u16 *buf) > > { > > - u8 i, len_words = len / sizeof(u16); > > - __be16 be_buf[MMA9551_MAX_MAILBOX_DATA_REGS]; > > + u8 i; > > + __be16 be_buf[(MMA9551_MAX_MAILBOX_DATA_REGS - 1) / 2]; > > + > > + if (len > ARRAY_SIZE(be_buf)) { > > + dev_err(&client->dev, "Invalid buffer size %d\n", len); > > + return -EINVAL; > > + } > > > > - for (i = 0; i < len_words; i++) > > + for (i = 0; i < len; i++) > > be_buf[i] = cpu_to_be16(buf[i]); > > > > return mma9551_transfer(client, app_id, MMA9551_CMD_WRITE_CONFIG, > > - reg, (u8 *) be_buf, len, NULL, 0); > > + reg, (u8 *)be_buf, len * sizeof(u16), NULL, 0); > > } > > EXPORT_SYMBOL(mma9551_write_config_words); > > > > diff --git a/drivers/iio/accel/mma9553.c b/drivers/iio/accel/mma9553.c > > index 96e4708..6991b01 100644 > > --- a/drivers/iio/accel/mma9553.c > > +++ b/drivers/iio/accel/mma9553.c > > @@ -322,7 +322,8 @@ static int mma9553_read_activity_stepcnt(struct > > mma9553_data *data, > > int ret; > > > > ret = mma9551_read_status_words(data->client, MMA9551_APPID_PEDOMETER, > > - MMA9553_REG_STATUS, sizeof(u32), buf); > > + MMA9553_REG_STATUS, ARRAY_SIZE(buf), > > + buf); > > if (ret < 0) { > > dev_err(&data->client->dev, > > "error reading status and stepcnt\n"); > > @@ -395,7 +396,7 @@ static int mma9553_init(struct mma9553_data *data) > > */ > > ret = mma9551_read_config_words(data->client, MMA9551_APPID_PEDOMETER, > > MMA9553_REG_CONF_SLEEPMIN, > > - sizeof(data->conf), > > + sizeof(data->conf) / sizeof(u16), > > (u16 *)&data->conf); > > if (ret < 0) { > > dev_err(&data->client->dev, > > @@ -428,7 +429,7 @@ static int mma9553_init(struct mma9553_data *data) > > MMA9553_MASK_CONF_ACT_DBCNTM); > > ret = mma9551_write_config_words(data->client, MMA9551_APPID_PEDOMETER, > > MMA9553_REG_CONF_SLEEPMIN, > > - sizeof(data->conf), > > + sizeof(data->conf) / sizeof(u16), > > (u16 *)&data->conf); > > if (ret < 0) { > > dev_err(&data->client->dev, > >
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