* Alexander Kochetkov <al.kochet@xxxxxxxxx> [141129 13:02]:
> commit dd74548ddece4b9d68e5528287a272fa552c81d0 ("i2c: omap:
> resize fifos before each message") dropped check for dev->buf_len.
> As result, data processing loop cause dev->buf overruns for
> devices with 16-bit data register (omap2420).
>
> In the dd74548ddece4b9d68 code, for each loop iteration if the
> flag OMAP_I2C_FLAG_16BIT_DATA_REG is set (omap2420), dev->buf
> is incremented twice, and dev->buf_len decremented twice.
>
> Also buffer overrun could happen (in theory) due to wrong
> ISR handling (bug).
>
> The commit fix data processing for omap2420 and add guard checks
> in the data processing loops do disallow accesses to the buffer,
> when dev->buf_len is zero. Also added warnings to unhide the bug.
>
> Found by code review.
>
> Signed-off-by: Alexander Kochetkov <al.kochet@xxxxxxxxx>
> Fixes: dd74548ddece4b9d68e5528287a272fa552c81d0 "i2c: omap: resize fifos before each message"
> Reported-by: Tony Lindgren <tony@xxxxxxxxxxx>
I think this is a different issue than what I'm seeing.
Not sure if I've seen what you're describing.. The $subject patch
should be reviewed by Felipe and Aaro, but this does not help
things on 2430.
Regards,
Tony
> drivers/i2c/busses/i2c-omap.c | 36 ++++++++++++++++++++++++++++--------
> 1 file changed, 28 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
> index 4563200..e890295 100644
> --- a/drivers/i2c/busses/i2c-omap.c
> +++ b/drivers/i2c/busses/i2c-omap.c
> @@ -938,20 +938,30 @@ static int errata_omap3_i462(struct omap_i2c_dev *dev)
> static void omap_i2c_receive_data(struct omap_i2c_dev *dev, u8 num_bytes,
> bool is_rdr)
> {
> - u16 w;
> + u16 w;
> +
> + if (unlikely(num_bytes > dev->buf_len)) {
> + dev_err(dev->dev, "%s interrupt can't receive %u byte(s)\n",
> + is_rdr ? "RDR" : "RRDY", (num_bytes - dev->buf_len));
> + num_bytes = dev->buf_len;
> + }
>
> - while (num_bytes--) {
> + while (num_bytes) {
> w = omap_i2c_read_reg(dev, OMAP_I2C_DATA_REG);
> *dev->buf++ = w;
> dev->buf_len--;
> + num_bytes--;
>
> /*
> * Data reg in 2430, omap3 and
> * omap4 is 8 bit wide
> */
> if (dev->flags & OMAP_I2C_FLAG_16BIT_DATA_REG) {
> - *dev->buf++ = w >> 8;
> - dev->buf_len--;
> + if (num_bytes) {
> + *dev->buf++ = w >> 8;
> + dev->buf_len--;
> + num_bytes--;
> + }
> }
> }
> }
> @@ -959,19 +969,29 @@ static void omap_i2c_receive_data(struct omap_i2c_dev *dev, u8 num_bytes,
> static int omap_i2c_transmit_data(struct omap_i2c_dev *dev, u8 num_bytes,
> bool is_xdr)
> {
> - u16 w;
> + u16 w;
> +
> + if (unlikely(num_bytes > dev->buf_len)) {
> + dev_err(dev->dev, "%s interrupt can't transmit %u byte(s)\n",
> + is_xdr ? "XDR" : "XRDY", (num_bytes - dev->buf_len));
> + num_bytes = dev->buf_len;
> + }
>
> - while (num_bytes--) {
> + while (num_bytes) {
> w = *dev->buf++;
> dev->buf_len--;
> + num_bytes--;
>
> /*
> * Data reg in 2430, omap3 and
> * omap4 is 8 bit wide
> */
> if (dev->flags & OMAP_I2C_FLAG_16BIT_DATA_REG) {
> - w |= *dev->buf++ << 8;
> - dev->buf_len--;
> + if (num_bytes) {
> + w |= *dev->buf++ << 8;
> + dev->buf_len--;
> + num_bytes--;
> + }
> }
>
> if (dev->errata & I2C_OMAP_ERRATA_I462) {
> --
> 1.7.9.5
>
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