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[media] mxl111sf: Fix potential null pointer dereference

Message ID 20170813100629.24034-1-rosca.eugeniu@gmail.com (mailing list archive)
State New, archived
Headers show

Commit Message

Eugeniu Rosca Aug. 13, 2017, 10:06 a.m. UTC 
From: Eugeniu Rosca <erosca@de.adit-jv.com>

Reviewing the delta between cppcheck output of v4.9.39 and v4.9.40
stable updates, I stumbled on the new warning:

mxl111sf.c:80: (warning) Possible null pointer dereference: rbuf

Since copying state->rcvbuf into rbuf is not needed in the 'write-only'
scenario (i.e. calling mxl111sf_ctrl_msg() from mxl111sf_i2c_send_data()
or from mxl111sf_write_reg()), bypass memcpy() in this case.

Fixes: d90b336f3f65 ("[media] mxl111sf: Fix driver to use heap allocate buffers for USB messages")
Signed-off-by: Eugeniu Rosca <erosca@de.adit-jv.com>
---
 drivers/media/usb/dvb-usb-v2/mxl111sf.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

Comments

Michael Ira Krufky Aug. 13, 2017, 12:31 p.m. UTC | #1 
On Sun, Aug 13, 2017 at 6:06 AM, Eugeniu Rosca <roscaeugeniu@gmail.com> wrote:
> From: Eugeniu Rosca <erosca@de.adit-jv.com>
>
> Reviewing the delta between cppcheck output of v4.9.39 and v4.9.40
> stable updates, I stumbled on the new warning:
>
> mxl111sf.c:80: (warning) Possible null pointer dereference: rbuf
>
> Since copying state->rcvbuf into rbuf is not needed in the 'write-only'
> scenario (i.e. calling mxl111sf_ctrl_msg() from mxl111sf_i2c_send_data()
> or from mxl111sf_write_reg()), bypass memcpy() in this case.
>
> Fixes: d90b336f3f65 ("[media] mxl111sf: Fix driver to use heap allocate buffers for USB messages")
> Signed-off-by: Eugeniu Rosca <erosca@de.adit-jv.com>
> ---
>  drivers/media/usb/dvb-usb-v2/mxl111sf.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)


Reviewed-by:  Michael Ira Krufky <mkrufky@linuxtv.org>


Thank you for this, Eugeniu




> diff --git a/drivers/media/usb/dvb-usb-v2/mxl111sf.c b/drivers/media/usb/dvb-usb-v2/mxl111sf.c
> index b0d5904a4ea6..67953360fda5 100644
> --- a/drivers/media/usb/dvb-usb-v2/mxl111sf.c
> +++ b/drivers/media/usb/dvb-usb-v2/mxl111sf.c
> @@ -77,7 +77,9 @@ int mxl111sf_ctrl_msg(struct mxl111sf_state *state,
>                 dvb_usbv2_generic_rw(d, state->sndbuf, 1+wlen, state->rcvbuf,
>                                      rlen);
>
> -       memcpy(rbuf, state->rcvbuf, rlen);
> +       if (rbuf)
> +               memcpy(rbuf, state->rcvbuf, rlen);
> +
>         mutex_unlock(&state->msg_lock);
>
>         mxl_fail(ret);
> --
> 2.14.1
>
diff mbox

Patch

diff --git a/drivers/media/usb/dvb-usb-v2/mxl111sf.c b/drivers/media/usb/dvb-usb-v2/mxl111sf.c
index b0d5904a4ea6..67953360fda5 100644
--- a/drivers/media/usb/dvb-usb-v2/mxl111sf.c
+++ b/drivers/media/usb/dvb-usb-v2/mxl111sf.c
@@ -77,7 +77,9 @@  int mxl111sf_ctrl_msg(struct mxl111sf_state *state,
 		dvb_usbv2_generic_rw(d, state->sndbuf, 1+wlen, state->rcvbuf,
 				     rlen);
 
-	memcpy(rbuf, state->rcvbuf, rlen);
+	if (rbuf)
+		memcpy(rbuf, state->rcvbuf, rlen);
+
 	mutex_unlock(&state->msg_lock);
 
 	mxl_fail(ret);