2023-03-30 09:36:18

by Mårten Lindahl

Subject: [PATCH v2] ubifs: Free memory for tmpfile name

When opening a ubifs tmpfile on an encrypted directory, function
fscrypt_setup_filename allocates memory for the name that is to be
stored in the directory entry, but after the name has been copied to the
directory entry inode, the memory is not freed.

When running kmemleak on it we see that it is registered as a leak. The
report below is triggered by a simple program 'tmpfile' just opening a
tmpfile:

unreferenced object 0xffff88810178f380 (size 32):
comm "tmpfile", pid 509, jiffies 4294934744 (age 1524.742s)
backtrace:
__kmem_cache_alloc_node
__kmalloc
fscrypt_setup_filename
ubifs_tmpfile
vfs_tmpfile
path_openat

Free this memory after it has been copied to the inode.

Signed-off-by: Mårten Lindahl <[email protected]>
---
Changes in v2:
- Call fscrypt_free_filename after ubifs_release_budget
- Link to v1: https://lore.kernel.org/r/[email protected]
---
fs/ubifs/dir.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/fs/ubifs/dir.c b/fs/ubifs/dir.c
index 0f29cf201136..7dd6dd34b84c 100644
--- a/fs/ubifs/dir.c
+++ b/fs/ubifs/dir.c
@@ -492,6 +492,7 @@ static int ubifs_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
unlock_2_inodes(dir, inode);

ubifs_release_budget(c, &req);
+ fscrypt_free_filename(&nm);

return finish_open_simple(file, 0);


---
base-commit: c9c3395d5e3dcc6daee66c6908354d47bf98cb0c
change-id: 20230329-memleak-fix-87a01daf469e

Best regards,
--
Mårten Lindahl <[email protected]>

2023-03-30 11:11:59

by Zhihao Cheng

Subject: Re: [PATCH v2] ubifs: Free memory for tmpfile name

> When opening a ubifs tmpfile on an encrypted directory, function
> fscrypt_setup_filename allocates memory for the name that is to be
> stored in the directory entry, but after the name has been copied to the
> directory entry inode, the memory is not freed.
>
> When running kmemleak on it we see that it is registered as a leak. The
> report below is triggered by a simple program 'tmpfile' just opening a
> tmpfile:
>
> unreferenced object 0xffff88810178f380 (size 32):
> comm "tmpfile", pid 509, jiffies 4294934744 (age 1524.742s)
> backtrace:
> __kmem_cache_alloc_node
> __kmalloc
> fscrypt_setup_filename
> ubifs_tmpfile
> vfs_tmpfile
> path_openat
>
> Free this memory after it has been copied to the inode.
>
> Signed-off-by: Mårten Lindahl <[email protected]>
> ---
> Changes in v2:
> - Call fscrypt_free_filename after ubifs_release_budget
> - Link to v1: https://lore.kernel.org/r/[email protected]
> ---
> fs/ubifs/dir.c | 1 +
> 1 file changed, 1 insertion(+)

Reviewed-by: Zhihao Cheng <[email protected]>

>
> diff --git a/fs/ubifs/dir.c b/fs/ubifs/dir.c
> index 0f29cf201136..7dd6dd34b84c 100644
> --- a/fs/ubifs/dir.c
> +++ b/fs/ubifs/dir.c
> @@ -492,6 +492,7 @@ static int ubifs_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
> unlock_2_inodes(dir, inode);
>
> ubifs_release_budget(c, &req);
> + fscrypt_free_filename(&nm);
>
> return finish_open_simple(file, 0);
>
>
> ---
> base-commit: c9c3395d5e3dcc6daee66c6908354d47bf98cb0c
> change-id: 20230329-memleak-fix-87a01daf469e
>
> Best regards,
>