From: Miklos Szeredi Date: Thu, 23 Oct 2014 22:14:39 +0000 (+0200) Subject: fs: limit filesystem stacking depth X-Git-Tag: v3.2.82~10 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9d6c5babc04522ff85b550f14563970279ab8f90;p=pandora-kernel.git fs: limit filesystem stacking depth commit 69c433ed2ecd2d3264efd7afec4439524b319121 upstream. Add a simple read-only counter to super_block that indicates how deep this is in the stack of filesystems. Previously ecryptfs was the only stackable filesystem and it explicitly disallowed multiple layers of itself. Overlayfs, however, can be stacked recursively and also may be stacked on top of ecryptfs or vice versa. To limit the kernel stack usage we must limit the depth of the filesystem stack. Initially the limit is set to 2. Signed-off-by: Miklos Szeredi [bwh: Backported to 3.2: - Drop changes to overlayfs - Adjust context] Signed-off-by: Ben Hutchings --- diff --git a/fs/ecryptfs/main.c b/fs/ecryptfs/main.c index 62b8ddc2c630..b53a97e43c91 100644 --- a/fs/ecryptfs/main.c +++ b/fs/ecryptfs/main.c @@ -576,6 +576,13 @@ 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); Reading git-diff-tree failed