[PATCH] shmem: fix __shmem_file_setup error path leaks

Vito Caputo
2017-03-27T17:04:42Z

The existing path and memory cleanups appear to be in reverse order, and
there's no iput() potentially leaking the inode in the last two error gotos.

Also make put_memory shmem_unacct_size() conditional on !inode since if we
entered cleanup at put_inode, shmem_evict_inode() occurs via
iput()->iput_final(), which performs the shmem_unacct_size() for us.

Signed-off-by: Vito Caputo <vcaputo@pengaru.com>
---

This caught my eye while looking through the memfd_create() implementation.
Included patch was compile tested only...

mm/shmem.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/mm/shmem.c b/mm/shmem.c
index e67d6ba..a1a84eaf 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -4134,7 +4134,7 @@ static struct file *__shmem_file_setup(const char *name, loff_t size,
unsigned long flags, unsigned int i_flags)
{
struct file *res;
- struct inode *inode;
+ struct inode *inode = NULL;
struct path path;
struct super_block *sb;
struct qstr this;
@@ -4162,7 +4162,7 @@ static struct file *__shmem_file_setup(const char *name, loff_t size,
res = ERR_PTR(-ENOSPC);
inode = shmem_get_inode(sb, NULL, S_IFREG | S_IRWXUGO, 0, flags);
if (!inode)
- goto put_memory;
+ goto put_path;

inode->i_flags |= i_flags;
d_instantiate(path.dentry, inode);
@@ -4170,19 +4170,22 @@ static struct file *__shmem_file_setup(const char *name, loff_t size,
clear_nlink(inode); /* It is unlinked */
res = ERR_PTR(ramfs_nommu_expand_for_mapping(inode, size));
if (IS_ERR(res))
- goto put_path;
+ goto put_inode;

res = alloc_file(&path, FMODE_WRITE | FMODE_READ,
&shmem_file_operations);
if (IS_ERR(res))
- goto put_path;
+ goto put_inode;

return res;

-put_memory:
- shmem_unacct_size(flags, size);
+put_inode:
+ iput(inode);
put_path:
path_put(&path);
+put_memory:
+ if (!inode)
+ shmem_unacct_size(flags, size);
return res;
}

--
2.1.4