diff options
| -rw-r--r-- | fs/ecryptfs/main.c | 7 | ||||
| -rw-r--r-- | fs/overlayfs/super.c | 9 | ||||
| -rw-r--r-- | include/linux/fs.h | 11 |
3 files changed, 27 insertions, 0 deletions
diff --git a/fs/ecryptfs/main.c b/fs/ecryptfs/main.c index 1b119d3bf924..c4cd1fd86cc2 100644 --- a/fs/ecryptfs/main.c +++ b/fs/ecryptfs/main.c @@ -566,6 +566,13 @@ static struct dentry *ecryptfs_mount(struct file_system_type *fs_type, int flags s->s_maxbytes = path.dentry->d_sb->s_maxbytes; s->s_blocksize = path.dentry->d_sb->s_blocksize; s->s_magic = ECRYPTFS_SUPER_MAGIC; + s->s_stack_depth = path.dentry->d_sb->s_stack_depth + 1; + + rc = -EINVAL; + if (s->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) { + pr_err("eCryptfs: maximum fs stacking depth exceeded\n"); + goto out_free; + } inode = ecryptfs_get_inode(path.dentry->d_inode, s); rc = PTR_ERR(inode); diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index 7dcc24e84417..08b704cebfc4 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -677,6 +677,15 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) } ufs->lower_namelen = statfs.f_namelen; + sb->s_stack_depth = max(upperpath.mnt->mnt_sb->s_stack_depth, + lowerpath.mnt->mnt_sb->s_stack_depth) + 1; + + err = -EINVAL; + if (sb->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) { + pr_err("overlayfs: maximum fs stacking depth exceeded\n"); + goto out_put_workpath; + } + ufs->upper_mnt = clone_private_mount(&upperpath); err = PTR_ERR(ufs->upper_mnt); if (IS_ERR(ufs->upper_mnt)) { diff --git a/include/linux/fs.h b/include/linux/fs.h index 69118b3cb917..4e41a4a331bb 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -261,6 +261,12 @@ struct iattr { */ #include <linux/quota.h> +/* + * Maximum number of layers of fs stack. Needs to be limited to + * prevent kernel stack overflow + */ +#define FILESYSTEM_MAX_STACK_DEPTH 2 + /** * enum positive_aop_returns - aop return codes with specific semantics * @@ -1273,6 +1279,11 @@ struct super_block { struct list_lru s_dentry_lru ____cacheline_aligned_in_smp; struct list_lru s_inode_lru ____cacheline_aligned_in_smp; struct rcu_head rcu; + + /* + * Indicates how deep in a filesystem stack this SB is + */ + int s_stack_depth; }; extern struct timespec current_fs_time(struct super_block *sb); |