| Message ID | 20211001123617.GH2283@kili (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | [1/3] drm/msm/dsi: Fix an error code in msm_dsi_modeset_init() | expand |
On 01/10/2021 15:36, Dan Carpenter wrote: > The "msg->tx_len" variable is type size_t so if dsi_cmds2buf_tx() > returns a negative error code that it type promoted to a high positive > value and treat as a success. The second problem with this code is > that it can return meaningless positive values on error. It looks to me that this piece of code is not fully correct at all. dsi_cmds2bus_tx would return the size of DSI packet, not the size of the DSI buffer. Could you please be more specific, which 'meaningless positive values' were you receiving? > > Fixes: a689554ba6ed ("drm/msm: Initial add DSI connector support") > Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> > --- > drivers/gpu/drm/msm/dsi/dsi_host.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c > index c86b5090fae6..42073a562072 100644 > --- a/drivers/gpu/drm/msm/dsi/dsi_host.c > +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c > @@ -2133,8 +2133,10 @@ int msm_dsi_host_cmd_rx(struct mipi_dsi_host *host, > } > > ret = dsi_cmds2buf_tx(msm_host, msg); > - if (ret < msg->tx_len) { > + if (ret < 0 || ret < msg->tx_len) { > pr_err("%s: Read cmd Tx failed, %d\n", __func__, ret); > + if (ret >= 0) > + ret = -EIO; > return ret; > } > >
On Sat, Oct 02, 2021 at 01:59:56AM +0300, Dmitry Baryshkov wrote: > On 01/10/2021 15:36, Dan Carpenter wrote: > > The "msg->tx_len" variable is type size_t so if dsi_cmds2buf_tx() > > returns a negative error code that it type promoted to a high positive > > value and treat as a success. The second problem with this code is > > that it can return meaningless positive values on error. > > It looks to me that this piece of code is not fully correct at all. > dsi_cmds2bus_tx would return the size of DSI packet, not the size of the DSI > buffer. > > Could you please be more specific, which 'meaningless positive values' were > you receiving? > Sorry, I misread the code. I thought it returned negatives or the number of bytes copied. (This is from static analysis btw). Anyway, returning only negatives is a much better way. I will fix this patch and resend. regards, dan carpenter
On Sat, Oct 02, 2021 at 01:59:56AM +0300, Dmitry Baryshkov wrote: > On 01/10/2021 15:36, Dan Carpenter wrote: > > The "msg->tx_len" variable is type size_t so if dsi_cmds2buf_tx() > > returns a negative error code that it type promoted to a high positive > > value and treat as a success. The second problem with this code is > > that it can return meaningless positive values on error. > > It looks to me that this piece of code is not fully correct at all. > dsi_cmds2bus_tx would return the size of DSI packet, not the size of the DSI > buffer. Ugh... I misread what you were saying. I was thinking I could just check for negatives. This sounds like struct_size() thing? > > Could you please be more specific, which 'meaningless positive values' were > you receiving? > Returning any positive values at this point is a bug. It's supposed to return the number of bytes that were recieved. And there is another bug as well: drivers/gpu/drm/msm/dsi/dsi_host.c 1370 static int dsi_cmds2buf_tx(struct msm_dsi_host *msm_host, 1371 const struct mipi_dsi_msg *msg) 1372 { 1373 int len, ret; 1374 int bllp_len = msm_host->mode->hdisplay * 1375 dsi_get_bpp(msm_host->format) / 8; 1376 1377 len = dsi_cmd_dma_add(msm_host, msg); 1378 if (!len) { The dsi_cmd_dma_add() returns negative error codes so this check should be "if (len <= 0) {". 1379 pr_err("%s: failed to add cmd type = 0x%x\n", 1380 __func__, msg->type); 1381 return -EINVAL; 1382 } 1383 I'm not sure about the size of "the DSI packet" Could you handle this one and give me a Reported-by tag? That's probably simpler than another back and forth on email. regards, dan carpenter
diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c index c86b5090fae6..42073a562072 100644 --- a/drivers/gpu/drm/msm/dsi/dsi_host.c +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c @@ -2133,8 +2133,10 @@ int msm_dsi_host_cmd_rx(struct mipi_dsi_host *host, } ret = dsi_cmds2buf_tx(msm_host, msg); - if (ret < msg->tx_len) { + if (ret < 0 || ret < msg->tx_len) { pr_err("%s: Read cmd Tx failed, %d\n", __func__, ret); + if (ret >= 0) + ret = -EIO; return ret; }
The "msg->tx_len" variable is type size_t so if dsi_cmds2buf_tx() returns a negative error code that it type promoted to a high positive value and treat as a success. The second problem with this code is that it can return meaningless positive values on error. Fixes: a689554ba6ed ("drm/msm: Initial add DSI connector support") Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> --- drivers/gpu/drm/msm/dsi/dsi_host.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)