linux-kernel - Re: [PATCH] drivers/mmc/card/block.c: fix potential null dereference 'idata'

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Date:	Mon, 09 May 2011 22:37:40 +0200
From:	Vladimir Motyka <vladimir.motyka@...il.com>
To:	Julia Lawall <julia@...u.dk>
CC:	cjb@...top.org, kernel-janitors@...r.kernel.org,
	linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drivers/mmc/card/block.c: fix potential null dereference
 'idata'

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(
 	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;
 	}

 	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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