Messages in this thread | | | From | Matthias Schwarzott <> | Subject | Re: [Patch] Zarlink zl10036 DVB-S: Fix mem leak in zl10036_attach | Date | Thu, 17 Feb 2011 21:45:51 +0100 |
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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@chaosbits.net>
Signed-off-by: Matthias Schwarzott <zzam@gentoo.org> > --- > 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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