From: Vladimir Motyka <vladimir.motyka@gmail.com>
To: Julia Lawall <julia@diku.dk>
Cc: cjb@laptop.org, kernel-janitors@vger.kernel.org,
linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] drivers/mmc/card/block.c: fix potential null dereference 'idata'
Date: Mon, 09 May 2011 17:05:36 +0200 [thread overview]
Message-ID: <4DC802C0.9040302@gmail.com> (raw)
In-Reply-To: <Pine.LNX.4.64.1105091631400.15483@pc-004.diku.dk>
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?
Vladimir Motyka
>
>> Signed-off-by: Vladimir Motyka <vladimir.motyka@gmail.com>
>>
>> ---
>> 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,
>> --
>> To unsubscribe from this list: send the line "unsubscribe kernel-janitors" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at http://vger.kernel.org/majordomo-info.html
>>
next prev parent reply other threads:[~2011-05-09 15:06 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-09 14:05 [PATCH] drivers/mmc/card/block.c: fix potential null dereference 'idata' Vladimir Motyka
2011-05-09 14:32 ` Julia Lawall
2011-05-09 15:05 ` Vladimir Motyka [this message]
2011-05-09 15:13 ` Andy Shevchenko
2011-05-09 15:14 ` Julia Lawall
2011-05-09 16:08 ` Vladimir Motyka
2011-05-09 16:12 ` Julia Lawall
2011-05-09 20:37 ` Vladimir Motyka
2011-05-09 20:37 ` Vladimir Motyka
2011-05-11 4:03 ` Chris Ball
2011-05-10 7:47 ` Andy Shevchenko
2011-05-10 7:57 ` Julia Lawall
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