drivers/mmc/card/block.c: fix potential null dereference 'idata'

Commit Message

Vladimir Motyka May 9, 2011, 8:37 p.m. UTC

When allocation of idata failed there was a null dereference. Also avoid
calling kfree where it is needn't.

---
 	if (copy_from_user(idata->buf, (void __user *)(unsigned long)
@@ -267,9 +267,10 @@ static struct mmc_blk_ioc_data
*mmc_blk_ioctl_copy_from_user(

 copy_err:
 	kfree(idata->buf);
+idata_err:
 	kfree(idata);
+out:
 	return ERR_PTR(err);
-
 }

 static int mmc_blk_ioctl_cmd(struct block_device *bdev,
--
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Comments

Chris Ball May 11, 2011, 4:03 a.m. UTC | #1

Hi,

On Mon, May 09 2011, Vladimir Motyka wrote:
> When allocation of idata failed there was a null dereference. Also avoid
> calling kfree where it is needn't.
>
> ---
> diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
> index 407836d..126c7f4 100644
> --- a/drivers/mmc/card/block.c
> +++ b/drivers/mmc/card/block.c
> @@ -237,24 +237,24 @@ static struct mmc_blk_ioc_data
> *mmc_blk_ioctl_copy_from_user(

Thanks, I've pushed this version of the patch to mmc-next.

(The patch you sent was corrupted by gmail; it added a line break on the
last line quoted above where there shouldn't be one.  Please fix that
for next time.)

- Chris.

Patch

diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
index 407836d..126c7f4 100644
--- a/drivers/mmc/card/block.c
+++ b/drivers/mmc/card/block.c
@@ -237,24 +237,24 @@  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 out;
 	}

 	if (copy_from_user(&idata->ic, user, sizeof(idata->ic))) {
 		err = -EFAULT;
-		goto copy_err;
+		goto idata_err;
 	}

 	idata->buf_bytes = (u64) idata->ic.blksz * idata->ic.blocks;
 	if (idata->buf_bytes > MMC_IOC_MAX_BYTES) {
 		err = -EOVERFLOW;
-		goto copy_err;
+		goto idata_err;
 	}

 	idata->buf = kzalloc(idata->buf_bytes, GFP_KERNEL);
 	if (!idata->buf) {
 		err = -ENOMEM;
-		goto copy_err;
+		goto idata_err;
 	}