@@ -1036,37 +1036,19 @@ struct ffs_sb_fill_data {
struct ffs_file_perms perms;
umode_t root_mode;
const char *dev_name;
- union {
- /* set by ffs_fs_mount(), read by ffs_sb_fill() */
- void *private_data;
- /* set by ffs_sb_fill(), read by ffs_fs_mount */
- struct ffs_data *ffs_data;
- };
+ struct ffs_data *ffs_data;
};
static int ffs_sb_fill(struct super_block *sb, void *_data, int silent)
{
struct ffs_sb_fill_data *data = _data;
struct inode *inode;
- struct ffs_data *ffs;
+ struct ffs_data *ffs = data->ffs_data;
ENTER();
- /* Initialise data */
- ffs = ffs_data_new();
- if (unlikely(!ffs))
- goto Enomem;
-
ffs->sb = sb;
- ffs->dev_name = kstrdup(data->dev_name, GFP_KERNEL);
- if (unlikely(!ffs->dev_name))
- goto Enomem;
- ffs->file_perms = data->perms;
- ffs->private_data = data->private_data;
-
- /* used by the caller of this function */
- data->ffs_data = ffs;
-
+ data->ffs_data = NULL;
sb->s_fs_info = ffs;
sb->s_blocksize = PAGE_CACHE_SIZE;
sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
@@ -1082,17 +1064,14 @@ static int ffs_sb_fill(struct super_block *sb, void *_data, int silent)
&data->perms);
sb->s_root = d_make_root(inode);
if (unlikely(!sb->s_root))
- goto Enomem;
+ return -ENOMEM;
/* EP0 file */
if (unlikely(!ffs_sb_create_file(sb, "ep0", ffs,
&ffs_ep0_operations, NULL)))
- goto Enomem;
+ return -ENOMEM;
return 0;
-
-Enomem:
- return -ENOMEM;
}
static int ffs_fs_parse_opts(struct ffs_sb_fill_data *data, char *opts)
@@ -1196,6 +1175,7 @@ ffs_fs_mount(struct file_system_type *t, int flags,
struct dentry *rv;
int ret;
void *ffs_dev;
+ struct ffs_data *ffs;
ENTER();
@@ -1203,18 +1183,30 @@ ffs_fs_mount(struct file_system_type *t, int flags,
if (unlikely(ret < 0))
return ERR_PTR(ret);
+ ffs = ffs_data_new();
+ if (unlikely(!ffs))
+ return ERR_PTR(-ENOMEM);
+ ffs->file_perms = data.perms;
+
+ ffs->dev_name = kstrdup(dev_name, GFP_KERNEL);
+ if (unlikely(!ffs->dev_name)) {
+ ffs_data_put(ffs);
+ return ERR_PTR(-ENOMEM);
+ }
+
ffs_dev = functionfs_acquire_dev_callback(dev_name);
- if (IS_ERR(ffs_dev))
- return ffs_dev;
+ if (IS_ERR(ffs_dev)) {
+ ffs_data_put(ffs);
+ return ERR_CAST(ffs_dev);
+ }
+ ffs->private_data = ffs_dev;
+ data.ffs_data = ffs;
- data.dev_name = dev_name;
- data.private_data = ffs_dev;
rv = mount_nodev(t, flags, &data, ffs_sb_fill);
-
- /* data.ffs_data is set by ffs_sb_fill */
- if (IS_ERR(rv))
+ if (IS_ERR(rv) && data.ffs_data) {
functionfs_release_dev_callback(data.ffs_data);
-
+ ffs_data_put(data.ffs_data);
+ }
return rv;
}
This is a note to let you know that I have just added a patch titled USB: Fix breakage in ffs_fs_mount() to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue This patch is scheduled to be released in version 3.8.13.11. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.8.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ------ From 6280996c06a1df3a03c3a23a7da11b6fdbf10670 Mon Sep 17 00:00:00 2001 From: Al Viro <viro@ZenIV.linux.org.uk> Date: Fri, 20 Sep 2013 17:14:21 +0100 Subject: USB: Fix breakage in ffs_fs_mount() commit 2606b28aabd7dea1766c23a105e1124c95409c96 upstream. There's a bunch of failure exits in ffs_fs_mount() with seriously broken recovery logics. Most of that appears to stem from misunderstanding of the ->kill_sb() semantics; unlike ->put_super() it is called for *all* superblocks of given type, no matter how (in)complete the setup had been. ->put_super() is called only if ->s_root is not NULL; any failure prior to setting ->s_root will have the call of ->put_super() skipped. ->kill_sb(), OTOH, awaits every superblock that has come from sget(). Current behaviour of ffs_fs_mount(): We have struct ffs_sb_fill_data data on stack there. We do ffs_dev = functionfs_acquire_dev_callback(dev_name); and store that in data.private_data. Then we call mount_nodev(), passing it ffs_sb_fill() as a callback. That will either fail outright, or manage to call ffs_sb_fill(). There we allocate an instance of struct ffs_data, slap the value of ffs_dev (picked from data.private_data) into ffs->private_data and overwrite data.private_data by storing ffs into an overlapping member (data.ffs_data). Then we store ffs into sb->s_fs_info and attempt to set the rest of the things up (root inode, root dentry, then create /ep0 there). Any of those might fail. Should that happen, we get ffs_fs_kill_sb() called before mount_nodev() returns. If mount_nodev() fails for any reason whatsoever, we proceed to functionfs_release_dev_callback(data.ffs_data); That's broken in a lot of ways. Suppose the thing has failed in allocation of e.g. root inode or dentry. We have functionfs_release_dev_callback(ffs); ffs_data_put(ffs); done by ffs_fs_kill_sb() (ffs accessed via sb->s_fs_info), followed by functionfs_release_dev_callback(ffs); from ffs_fs_mount() (via data.ffs_data). Note that the second functionfs_release_dev_callback() has every chance to be done to freed memory. Suppose we fail *before* root inode allocation. What happens then? ffs_fs_kill_sb() doesn't do anything to ffs (it's either not called at all, or it doesn't have a pointer to ffs stored in sb->s_fs_info). And functionfs_release_dev_callback(data.ffs_data); is called by ffs_fs_mount(), but here we are in nasal daemon country - we are reading from a member of union we'd never stored into. In practice, we'll get what we used to store into the overlapping field, i.e. ffs_dev. And then we get screwed, since we treat it (struct gfs_ffs_obj * in disguise, returned by functionfs_acquire_dev_callback()) as struct ffs_data *, pick what would've been ffs_data ->private_data from it (*well* past the actual end of the struct gfs_ffs_obj - struct ffs_data is much bigger) and poke in whatever it points to. FWIW, there's a minor leak on top of all that in case if ffs_sb_fill() fails on kstrdup() - ffs is obviously forgotten. The thing is, there is no point in playing all those games with union. Just allocate and initialize ffs_data *before* calling mount_nodev() and pass a pointer to it via data.ffs_data. And once it's stored in sb->s_fs_info, clear data.ffs_data, so that ffs_fs_mount() knows that it doesn't need to kill the sucker manually - from that point on we'll have it done by ->kill_sb(). Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Acked-by: Michal Nazarewicz <mina86@mina86.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- drivers/usb/gadget/f_fs.c | 60 ++++++++++++++++++++--------------------------- 1 file changed, 26 insertions(+), 34 deletions(-) -- 1.8.1.2