[PATCH] firmware: Google VPD: Fix memory allocation error handling

[PATCH] firmware: Google VPD: Fix memory allocation error handling

[Christophe JAILLET]

This patch fixes several issues:
   - if the 1st 'kzalloc' fails, we dereference a NULL pointer
   - if the 2nd 'kzalloc' fails, there is a memory leak
   - if 'sysfs_create_bin_file' fails there is also a memory leak

Fix it by adding a test after the first memory allocation and some error
handling paths to correctly free memory if needed.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
---
 drivers/firmware/google/vpd.c | 21 +++++++++++++++------
 1 file changed, 15 insertions(+), 6 deletions(-)

diff --git a/drivers/firmware/google/vpd.c b/drivers/firmware/google/vpd.c
index 619f4bae474f..2a1b0040a220 100644
--- a/drivers/firmware/google/vpd.c
+++ b/drivers/firmware/google/vpd.c
@@ -116,9 +116,13 @@ static int vpd_section_attrib_add(const u8 *key, s32 key_len,
 		return VPD_OK;
 
 	info = kzalloc(sizeof(*info), GFP_KERNEL);
-	info->key = kzalloc(key_len + 1, GFP_KERNEL);
-	if (!info->key)
+	if (!info)
 		return -ENOMEM;
+	info->key = kzalloc(key_len + 1, GFP_KERNEL);
+	if (!info->key) {
+		ret = -ENOMEM;
+		goto free_info;
+	}
 
 	memcpy(info->key, key, key_len);
 
@@ -135,12 +139,17 @@ static int vpd_section_attrib_add(const u8 *key, s32 key_len,
 	list_add_tail(&info->list, &sec->attribs);
 
 	ret = sysfs_create_bin_file(sec->kobj, &info->bin_attr);
-	if (ret) {
-		kfree(info->key);
-		return ret;
-	}
+	if (ret)
+		goto free_info_key;
 
 	return 0;
+
+free_info_key:
+	kfree(info->key);
+free_info:
+	kfree(info);
+
+	return ret;
 }
 
 static void vpd_section_attrib_destroy(struct vpd_section *sec)
-- 
2.11.0

Re: [PATCH] firmware: Google VPD: Fix memory allocation error handling

[Greg KH]

On Fri, May 05, 2017 at 09:08:44PM +0200, Christophe JAILLET wrote:
> This patch fixes several issues:
>    - if the 1st 'kzalloc' fails, we dereference a NULL pointer
>    - if the 2nd 'kzalloc' fails, there is a memory leak
>    - if 'sysfs_create_bin_file' fails there is also a memory leak

Then it should be multiple patches, not fixing 3 things in one patch,
right?

thanks,

greg k-h

Re: [PATCH] firmware: Google VPD: Fix memory allocation error handling

[Christophe JAILLET]

Le 05/05/2017 à 21:56, Greg KH a écrit :
> On Fri, May 05, 2017 at 09:08:44PM +0200, Christophe JAILLET wrote:
>> This patch fixes several issues:
>>     - if the 1st 'kzalloc' fails, we dereference a NULL pointer
>>     - if the 2nd 'kzalloc' fails, there is a memory leak
>>     - if 'sysfs_create_bin_file' fails there is also a memory leak
> Then it should be multiple patches, not fixing 3 things in one patch,
> right?
>
> thanks,
>
> greg k-h
>
I can split it if you want, but the 3 points are more or less related 
and all belong to the same few lines of code. I didn't think having 3 
patches was needed in this case. I just wanted to give a detailed changelog.
If the commit message was only "This patch fixes memory allocation error 
handling in fct xxx' (as in the topic), I guess it would has been 
accepted (if it is correct of course) as-is.

Just tell me if you really prefer 3 patches, and I will resubmit.

CJ

Re: [PATCH] firmware: Google VPD: Fix memory allocation error handling

[Dan Carpenter]

On Fri, May 05, 2017 at 12:56:47PM -0700, Greg KH wrote:
> On Fri, May 05, 2017 at 09:08:44PM +0200, Christophe JAILLET wrote:
> > This patch fixes several issues:
> >    - if the 1st 'kzalloc' fails, we dereference a NULL pointer
> >    - if the 2nd 'kzalloc' fails, there is a memory leak
> >    - if 'sysfs_create_bin_file' fails there is also a memory leak
> 
> Then it should be multiple patches, not fixing 3 things in one patch,
> right?
> 

I agree with Christophe that this is basically one thing.  Otherwise you
end up breaking it up how Elfring does it into tiny tiny snippets that I
can't read.  Doing it this way is easier to review for me.

regards,
dan carpenter