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2606b28aab
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> Cc: stable <stable@vger.kernel.org> # 3.3+ Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
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| early | ||
| gadget | ||
| host | ||
| image | ||
| misc | ||
| mon | ||
| musb | ||
| phy | ||
| renesas_usbhs | ||
| serial | ||
| storage | ||
| wusbcore | ||
| Kconfig | ||
| Makefile | ||
| README | ||
| usb-common.c | ||
| usb-skeleton.c | ||
To understand all the Linux-USB framework, you'll use these resources:
* This source code. This is necessarily an evolving work, and
includes kerneldoc that should help you get a current overview.
("make pdfdocs", and then look at "usb.pdf" for host side and
"gadget.pdf" for peripheral side.) Also, Documentation/usb has
more information.
* The USB 2.0 specification (from www.usb.org), with supplements
such as those for USB OTG and the various device classes.
The USB specification has a good overview chapter, and USB
peripherals conform to the widely known "Chapter 9".
* Chip specifications for USB controllers. Examples include
host controllers (on PCs, servers, and more); peripheral
controllers (in devices with Linux firmware, like printers or
cell phones); and hard-wired peripherals like Ethernet adapters.
* Specifications for other protocols implemented by USB peripheral
functions. Some are vendor-specific; others are vendor-neutral
but just standardized outside of the www.usb.org team.
Here is a list of what each subdirectory here is, and what is contained in
them.
core/ - This is for the core USB host code, including the
usbfs files and the hub class driver ("khubd").
host/ - This is for USB host controller drivers. This
includes UHCI, OHCI, EHCI, and others that might
be used with more specialized "embedded" systems.
gadget/ - This is for USB peripheral controller drivers and
the various gadget drivers which talk to them.
Individual USB driver directories. A new driver should be added to the
first subdirectory in the list below that it fits into.
image/ - This is for still image drivers, like scanners or
digital cameras.
../input/ - This is for any driver that uses the input subsystem,
like keyboard, mice, touchscreens, tablets, etc.
../media/ - This is for multimedia drivers, like video cameras,
radios, and any other drivers that talk to the v4l
subsystem.
../net/ - This is for network drivers.
serial/ - This is for USB to serial drivers.
storage/ - This is for USB mass-storage drivers.
class/ - This is for all USB device drivers that do not fit
into any of the above categories, and work for a range
of USB Class specified devices.
misc/ - This is for all USB device drivers that do not fit
into any of the above categories.