On Mon, 9 May 2011, Vladimir Motyka wrote:
> On 05/09/2011 04:32 PM, Julia Lawall wrote:
> > On Mon, 9 May 2011, Vladimir Motyka wrote:
> >
> >> When allocation of idata fails there was a null dereferece.
> >
> > Why not have a different label for the two cases? That would make the
> > code easier to statically analyze, and perhaps be more understandable as
> > well.
> >
> > julia
> >
> I think You are right. So it could be better like this?
>
> diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
> index 3dec493..a03cdc6 100644
> --- a/drivers/mmc/card/block.c
> +++ b/drivers/mmc/card/block.c
> @@ -237,7 +237,7 @@ static struct mmc_blk_ioc_data
> *mmc_blk_ioctl_copy_from_user(
> idata = kzalloc(sizeof(*idata), GFP_KERNEL);
> if (!idata) {
> err = -ENOMEM;
> - goto copy_err;
> + goto alloc_err;
> }
>
> if (copy_from_user(&idata->ic, user, sizeof(idata->ic))) {
> @@ -266,9 +266,9 @@ static struct mmc_blk_ioc_data
> *mmc_blk_ioctl_copy_from_user(
> return idata;
>
> copy_err:
> - if(idata)
> - kfree(idata->buf);
> + kfree(idata->buf);
> kfree(idata);
> +alloc_err:
> return ERR_PTR(err);
> }
>
> Or it could return right after allocation fails so there needn't be
> goto. It is simplier, but maybe worse looking and to read. What is your
> opinion?
Perhaps it is also pointless to call kfree on something that is known to
be NULL. But I think that there is quite some code that does that, so
others might have another opinion.
julia
>
> Vladimir Motyka
>
> >
> >> Signed-off-by: Vladimir Motyka <vladimir.motyka@xxxxxxxxx>
> >>
> >> ---
> >> diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
> >> index 407836d..3dec493 100644
> >> --- a/drivers/mmc/card/block.c
> >> +++ b/drivers/mmc/card/block.c
> >> @@ -266,10 +266,10 @@ static struct mmc_blk_ioc_data
> >> *mmc_blk_ioctl_copy_from_user(
> >> return idata;
> >>
> >> copy_err:
> >> - kfree(idata->buf);
> >> + if(idata)
> >> + kfree(idata->buf);
> >> kfree(idata);
> >> return ERR_PTR(err);
> >> -
> >> }
> >>
> >> static int mmc_blk_ioctl_cmd(struct block_device *bdev,
> >> --
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> >>
>
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