On Thursday 17 February 2011, Jesper Juhl wrote:
> On Thu, 17 Feb 2011, Matthias Schwarzott wrote:
> > On Sunday 06 February 2011, Jesper Juhl wrote:
> > > If the memory allocation to 'state' succeeds but we jump to the 'error'
> > > label before 'state' is assigned to fe->tuner_priv, then the call to
> > > 'zl10036_release(fe)' at the 'error:' label will not free 'state', but
> > > only what was previously assigned to 'tuner_priv', thus leaking the
> > > memory allocated to 'state'.
> > > There are may ways to fix this, including assigning the allocated
> > > memory directly to 'fe->tuner_priv', but I did not go for that since
> > > the additional pointer derefs are more expensive than the local
> > > variable, so I just added a 'kfree(state)' call. I guess the call to
> > > 'zl10036_release' might not even be needed in this case, but I wasn't
> > > sure, so I left it in.
> >
> > Yeah, that call to zl10036_release can be completely eleminated.
> > Another thing is: jumping to the error label only makes sense when memory
> > was already allocated. So the jump in line 471 can be replaced by
> > "return NULL",
> >
> > as the other error handling before allocation:
> > if (NULL == config) {
> >
> > printk(KERN_ERR "%s: no config specified", __func__);
> > goto error;
> >
> > }
> >
> > I suggest to improve the patch to clean the code up when changing that.
> >
> > But I am fine with commiting this patch also if you do not want to change
> > it.
>
> Thank you for your feedback. It makes a lot of sense.
> Changing it is not a problem :)
> How about the updated patch below?
>
Looks good.
@Mauro: Please apply.
>
> If the memory allocation to 'state' succeeds but we jump to the 'error'
> label before 'state' is assigned to fe->tuner_priv, then the call to
> 'zl10036_release(fe)' at the 'error:' label will not free 'state', but
> only what was previously assigned to 'tuner_priv', thus leaking the memory
> allocated to 'state'.
> This patch fixes the leak and also does not jump to 'error:' before mem
> has been allocated but instead just returns. Also some small style
> cleanups.
>
> Signed-off-by: Jesper Juhl <jj@xxxxxxxxxxxxx>
Signed-off-by: Matthias Schwarzott <zzam@xxxxxxxxxx>
> ---
> zl10036.c | 10 +++++-----
> 1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/media/dvb/frontends/zl10036.c
> b/drivers/media/dvb/frontends/zl10036.c index 4627f49..81aa984 100644
> --- a/drivers/media/dvb/frontends/zl10036.c
> +++ b/drivers/media/dvb/frontends/zl10036.c
> @@ -463,16 +463,16 @@ struct dvb_frontend *zl10036_attach(struct
> dvb_frontend *fe, const struct zl10036_config *config,
> struct i2c_adapter *i2c)
> {
> - struct zl10036_state *state = NULL;
> + struct zl10036_state *state;
> int ret;
>
> - if (NULL == config) {
> + if (!config) {
> printk(KERN_ERR "%s: no config specified", __func__);
> - goto error;
> + return NULL;
> }
>
> state = kzalloc(sizeof(struct zl10036_state), GFP_KERNEL);
> - if (NULL == state)
> + if (!state)
> return NULL;
>
> state->config = config;
> @@ -507,7 +507,7 @@ struct dvb_frontend *zl10036_attach(struct dvb_frontend
> *fe, return fe;
>
> error:
> - zl10036_release(fe);
> + kfree(state);
> return NULL;
> }
> EXPORT_SYMBOL(zl10036_attach);
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