2019-03-24 22:50:14

by Kangjie Lu

Subject: [PATCH] thunderbolt: property: fix a buffer overflow and a missing check

First, no memory is allocated for "property->value.text"; the
following strcpy will lead to a buffer overflow.

Second, no check is enforced for the return value of kzalloc,
which may lead to NULL-pointer dereference.

The patch fixes the two issues.

Signed-off-by: Kangjie Lu <[email protected]>
---
drivers/thunderbolt/property.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/thunderbolt/property.c b/drivers/thunderbolt/property.c
index 841314deb446..d5b0cdb8f0b1 100644
--- a/drivers/thunderbolt/property.c
+++ b/drivers/thunderbolt/property.c
@@ -587,7 +587,12 @@ int tb_property_add_text(struct tb_property_dir *parent, const char *key,
return -ENOMEM;

property->length = size / 4;
- property->value.data = kzalloc(size, GFP_KERNEL);
+ property->value.text = kzalloc(size, GFP_KERNEL);
+ if (!property->value.text) {
+ kfree(property);
+ return -ENOMEM;
+ }
+
strcpy(property->value.text, text);

list_add_tail(&property->list, &parent->properties);
--
2.17.1

2019-03-25 10:02:10

by Mika Westerberg

Subject: Re: [PATCH] thunderbolt: property: fix a buffer overflow and a missing check

On Sun, Mar 24, 2019 at 05:49:16PM -0500, Kangjie Lu wrote:
> First, no memory is allocated for "property->value.text"; the
> following strcpy will lead to a buffer overflow.

It is actually member of union so assigning via value.txt or value.data
is the same.

So no buffer overflow.

> Second, no check is enforced for the return value of kzalloc,
> which may lead to NULL-pointer dereference.

Yes, this is valid.

Can you fix the changelog accordingly and resend?

>
> The patch fixes the two issues.
>
> Signed-off-by: Kangjie Lu <[email protected]>
> ---
> drivers/thunderbolt/property.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/thunderbolt/property.c b/drivers/thunderbolt/property.c
> index 841314deb446..d5b0cdb8f0b1 100644
> --- a/drivers/thunderbolt/property.c
> +++ b/drivers/thunderbolt/property.c
> @@ -587,7 +587,12 @@ int tb_property_add_text(struct tb_property_dir *parent, const char *key,
> return -ENOMEM;
>
> property->length = size / 4;
> - property->value.data = kzalloc(size, GFP_KERNEL);
> + property->value.text = kzalloc(size, GFP_KERNEL);
> + if (!property->value.text) {
> + kfree(property);
> + return -ENOMEM;
> + }
> +
> strcpy(property->value.text, text);
>
> list_add_tail(&property->list, &parent->properties);
> --
> 2.17.1

2019-03-27 14:47:36

by Mukesh Ojha

Subject: Re: [PATCH] thunderbolt: property: fix a buffer overflow and a missing check

On 3/25/2019 4:19 AM, Kangjie Lu wrote:
> First, no memory is allocated for "property->value.text"; the
> following strcpy will lead to a buffer overflow.

Fix the commit text as there is no  overflow.

only the check and resource cleanp is the fix.

>
> Second, no check is enforced for the return value of kzalloc,
> which may lead to NULL-pointer dereference.
>
> The patch fixes the two issues.
>
> Signed-off-by: Kangjie Lu <[email protected]
Otherwise looks good.

Reviewed-by: Mukesh Ojha <[email protected]>

-Mukesh

> ---
> drivers/thunderbolt/property.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/thunderbolt/property.c b/drivers/thunderbolt/property.c
> index 841314deb446..d5b0cdb8f0b1 100644
> --- a/drivers/thunderbolt/property.c
> +++ b/drivers/thunderbolt/property.c
> @@ -587,7 +587,12 @@ int tb_property_add_text(struct tb_property_dir *parent, const char *key,
> return -ENOMEM;
>
> property->length = size / 4;
> - property->value.data = kzalloc(size, GFP_KERNEL);
> + property->value.text = kzalloc(size, GFP_KERNEL);
> + if (!property->value.text) {
> + kfree(property);
> + return -ENOMEM;
> + }
> +
> strcpy(property->value.text, text);
>
> list_add_tail(&property->list, &parent->properties);