Chuck Ebbert <[email protected]> wrote:
>
> In-Reply-To: <[email protected]>
>
> On Tue, 10 Jan 2006 Helge Hafting wrote:
>
> > Kernel 2.6.15 amd64, gcc 4.1.0 from debian.
> >
> > The cdrom (/dev/hda) is usually fine. I tried booting with
> > hda=ide-scsi in order to read a scratched audio cd with cdparanoia.
> > That way, I at least get error messages when the scratches are
> > too bad.
> >
> > I forgot about hda=ide-scsi, and tried to mount /dev/hda as
> > usual in order to read an ordinary iso9660 cd. This is
> > probably not supposed to work when ide-scsi is using the device,
> > but then I expect something like EBUSY rather than this oops:
> >
> > ide-scsi: unsup command: dev hda: flags = REQ_SORTED REQ_CMD REQ_STARTED
> > REQ_ELVPRIV
> > sector 64, nr/cnr 2/2
> > bio ffff8100044a9b40, biotail ffff8100044a9b40, buffer ffff81000cb4d000, data
> > 0000000000000000, len 0
> > end_request: I/O error, dev hda, sector 64
> > isofs_fill_super: bread failed, dev=hda, iso_blknum=16, block=32
> > Unable to handle kernel NULL pointer dereference at 0000000000000000 RIP:
> > <ffffffff80235a92>{strlen+2}
>
>
> The IDE driver probably shouldn't have allowed the bdev to be opened in
> the first place.
>
> After that happened, mount attempted to fill the superblock and the I/O
> failed. Upon failure, get_sb_bdev() called deactivate_super()
> (fs/super.c line 718) and all hell broke loose.
>
> - deactivate_super() called fs->kill_sb() (super.c line 176) which
> pointed to kill_block_super() (fs/isofs/inode.c line 1411)
>
> - kill_block_super() called kobject_uevent() with action KOBJ_UMOUNT
> (Question: why is it sending UMOUNT for a mount that never happened?)
Happily, all that code just got deleted:
Also the new poll() interface to /proc/mounts is a nicer way to
notify about changes than sending events through the core.
The uevents should only be used for driver core related requests to
userspace now.
I dunno how this removal works with forward- and backward- compatible
userspace. Maybe it doesn't.
> - kobject_uevent() called kobject_get_path() and one of the objects
> had a null kobject.name, which caused strlen() to oops.
> There seem to be several bugs here:
>
> (1) IDE shouldn't have allowed the bdev to be opened.
Maybe. We've got in trouble in the past with making mounts try to get
exclusive access. I can't immediately remember what the problem was.
> (2) (maybe) kobject_uevent shouldn't have been called for an unmount event
> when the mount never succeeded.
Sounds reasonable.
> (3) kobject_get_path() shouldn't oops when a path component has a NULL name,
> or else kobject should fail registration of any such object.
The printk in kobject_register() will oops if kobj->name is null, so yes,
it seems reasonable to make kobject_register() fail up-front if there's no
->name. Greg agree?
Helge, it would be good if you could try the same trick on 2.6.15-git9 or
-git10, see if it behaves correctly.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
