[PATCH master] fs: ubootvarfs: fix double-free unlinking U-Boot variables

[PATCH master] fs: ubootvarfs: fix double-free unlinking U-Boot variables

[Ahmad Fatoum]

We free the struct ubootvarfs_inode::var as part of destroy_inode. In
case we have unlinked the U-Boot variable beforehand, we will end up
double-freeing. Set the member to NULL, so it's skipped in
destory_inode. We keep the free in destroy_inode, because that's still
needed for all the other inodes that aren't unlinked.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
 fs/ubootvarfs.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/ubootvarfs.c b/fs/ubootvarfs.c
index 475e4b7a79c4..147fee1ea631 100644
--- a/fs/ubootvarfs.c
+++ b/fs/ubootvarfs.c
@@ -259,6 +259,7 @@ static int ubootvarfs_unlink(struct inode *dir, struct dentry *dentry)
 
 		list_del(&var->list);
 		free(var);
+		node->var = NULL;
 	}
 
 	return simple_unlink(dir, dentry);
-- 
2.30.2

Re: [PATCH master] fs: ubootvarfs: fix double-free unlinking U-Boot variables

[Sascha Hauer]

On Fri, Aug 19, 2022 at 12:55:21PM +0200, Ahmad Fatoum wrote:
> We free the struct ubootvarfs_inode::var as part of destroy_inode. In
> case we have unlinked the U-Boot variable beforehand, we will end up
> double-freeing. Set the member to NULL, so it's skipped in
> destory_inode. We keep the free in destroy_inode, because that's still
> needed for all the other inodes that aren't unlinked.
> 
> Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
> ---
>  fs/ubootvarfs.c | 1 +
>  1 file changed, 1 insertion(+)

Applied, thanks

Sascha

> 
> diff --git a/fs/ubootvarfs.c b/fs/ubootvarfs.c
> index 475e4b7a79c4..147fee1ea631 100644
> --- a/fs/ubootvarfs.c
> +++ b/fs/ubootvarfs.c
> @@ -259,6 +259,7 @@ static int ubootvarfs_unlink(struct inode *dir, struct dentry *dentry)
>  
>  		list_del(&var->list);
>  		free(var);
> +		node->var = NULL;
>  	}
>  
>  	return simple_unlink(dir, dentry);
> -- 
> 2.30.2
> 
> 
> 

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