[PATCH] ubifs: Free memory for tmpfile name
martenli at axis.com
Thu Mar 30 00:54:46 PDT 2023
On 3/30/23 04:25, Zhihao Cheng wrote:
> Hi Mårten,
>> 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
>> unreferenced object 0xffff88810178f380 (size 32):
>> comm "tmpfile", pid 509, jiffies 4294934744 (age 1524.742s)
>> Free this memory after it has been copied to the inode.
>> Signed-off-by: Mårten Lindahl <marten.lindahl at axis.com>
>> fs/ubifs/dir.c | 1 +
>> 1 file changed, 1 insertion(+)
>> diff --git a/fs/ubifs/dir.c b/fs/ubifs/dir.c
>> index 0f29cf201136..089ca6910124 100644
>> --- a/fs/ubifs/dir.c
>> +++ b/fs/ubifs/dir.c
>> @@ -491,6 +491,7 @@ static int ubifs_tmpfile(struct user_namespace
>> *mnt_userns, struct inode *dir,
>> goto out_cancel;
>> unlock_2_inodes(dir, inode);
>> + fscrypt_free_filename(&nm);
>> ubifs_release_budget(c, &req);
>> return finish_open_simple(file, 0);
> Looks good, just one small nit. I'd prefer to add
> fscrypt_free_filename() after ubifs_release_budget() just like
> ubifs_create/link does, so that ubifs can get unused budget earlier.
OK, I will move it after ubifs_release_budget.
> After looking through the code, I found another place create_whiteout
> has the same problem(Imported in 278d9a243635f26c05("ubifs: Rename
> whiteout atomically") by me). Would you mind fixing this point just by
> removing unused 'nm' in create_whiteout()?
I see what you mean. As I understand it calling fscrypt_setup_filename
is not needed in create_whiteout. I would prefer removing those lines in
a separate patch since that leak is related to do_rename(). If it's OK
with you I can make a patch for that. Would that be OK?
>> base-commit: c9c3395d5e3dcc6daee66c6908354d47bf98cb0c
>> change-id: 20230329-memleak-fix-87a01daf469e
>> Best regards,
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