[PATCH] mtd: check parts pointer before using it

The code has the check for parts but it called after kmemdup,
kmemdup(parts, sizeof(*parts) * nr_parts,...)
if (!parts)
	return -ENOMEM

In fact, we need check parts before safely using it.

Signed-off-by: Jason Liu <redacted>
Cc: Dmitry Eremin-Solenikov <redacted>
Cc: Artem Bityutskiy <redacted>

---
This patch is based on git://git.infradead.org/users/dedekind/l2-mtd-2.6.git
---
 drivers/mtd/mtdcore.c |    4 +---
 1 files changed, 1 insertions(+), 3 deletions(-)

diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index 09bdbac..ce59ff5 100644
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c

@@ -465,12 +465,10 @@ int mtd_device_parse_register(struct mtd_info *mtd, const char **types,
 	struct mtd_partition *real_parts;
 
 	err = parse_mtd_partitions(mtd, types, &real_parts, parser_data);
-	if (err <= 0 && nr_parts) {
+	if (err <= 0 && nr_parts && !parts) {
 		real_parts = kmemdup(parts, sizeof(*parts) * nr_parts,
 				     GFP_KERNEL);
 		err = nr_parts;
-		if (!parts)
-			err = -ENOMEM;
 	}
 
 	if (err > 0) {

-- 
1.7.4.1

Hi Jason,

On Wed, Aug 24, 2011 at 06:53:01PM +0800, Jason Liu wrote:

I don't think this is right.  Don't we want to check that parts is != 
NULL?  So

	if (err <= 0 && nr_parts && parts)

instead?  We don't want to kmemdup() NULL.

 		real_parts = kmemdup(parts, sizeof(*parts) * nr_parts,
 				     GFP_KERNEL);
 		err = nr_parts;
-		if (!parts)
-			err = -ENOMEM;

I think this hunk should be changed to:

		if (!real_parts)
			err = -ENOMEM;

and keep the check so that we're checking kmemdup()'s allocation is 
successful.

Jamie

2011/8/24 Jamie Iles [off-list ref]:

Hi Jason,

On Wed, Aug 24, 2011 at 06:53:01PM +0800, Jason Liu wrote:

quoted

The code has the check for parts but it called after kmemdup,
kmemdup(parts, sizeof(*parts) * nr_parts,...)
if (!parts)
? ? ? return -ENOMEM

In fact, we need check parts before safely using it.

Signed-off-by: Jason Liu <redacted>
Cc: Dmitry Eremin-Solenikov <redacted>
Cc: Artem Bityutskiy <redacted>

---
This patch is based on git://git.infradead.org/users/dedekind/l2-mtd-2.6.git
---
?drivers/mtd/mtdcore.c | ? ?4 +---
?1 files changed, 1 insertions(+), 3 deletions(-)

diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index 09bdbac..ce59ff5 100644
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c

@@ -465,12 +465,10 @@ int mtd_device_parse_register(struct mtd_info *mtd, const char **types,

? ? ? struct mtd_partition *real_parts;

? ? ? err = parse_mtd_partitions(mtd, types, &real_parts, parser_data);
- ? ? if (err <= 0 && nr_parts) {
+ ? ? if (err <= 0 && nr_parts && !parts) {

I don't think this is right. ?Don't we want to check that parts is !=
NULL? ?So

? ? ? ?if (err <= 0 && nr_parts && parts)

instead? ?We don't want to kmemdup() NULL.

My bad,  I type it error. Thanks for it.

quoted

? ? ? ? ? ? ? real_parts = kmemdup(parts, sizeof(*parts) * nr_parts,
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?GFP_KERNEL);
? ? ? ? ? ? ? err = nr_parts;
- ? ? ? ? ? ? if (!parts)
- ? ? ? ? ? ? ? ? ? ? err = -ENOMEM;

I think this hunk should be changed to:

? ? ? ? ? ? ? ?if (!real_parts)
? ? ? ? ? ? ? ? ? ? ? ?err = -ENOMEM;

and keep the check so that we're checking kmemdup()'s allocation is
successful.

Yes, correct. Thanks,

Jamie
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