Messages in this thread | | | Date | Thu, 7 May 2015 15:59:19 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH] devpts: If initialization failed, don't crash when opening /dev/ptmx |
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On Wed, 6 May 2015 17:35:47 -0700 Josh Triplett <josh@joshtriplett.org> wrote:
> If devpts failed to initialize, it would store an ERR_PTR in the global > devpts_mnt. A subsequent open of /dev/ptmx would call devpts_new_index, > which would dereference devpts_mnt and crash. > > Avoid storing invalid values in devpts_mnt; leave it NULL instead. > Make both devpts_new_index and devpts_pty_new fail gracefully with > ENODEV in that case, which then becomes the return value to the > userspace open call on /dev/ptmx.
It looks like the system is pretty crippled if init_devptr_fs() fails. Can the user actually get access to consoles and do useful things in this situation? Maybe it would be better to just give up and panic?
> @@ -676,12 +689,15 @@ static int __init init_devpts_fs(void) > struct ctl_table_header *table; > > if (!err) { > + static struct vfsmount *mnt;
static is weird. I assume this was a braino?
> table = register_sysctl_table(pty_root_table); > - devpts_mnt = kern_mount(&devpts_fs_type); > - if (IS_ERR(devpts_mnt)) { > - err = PTR_ERR(devpts_mnt); > + mnt = kern_mount(&devpts_fs_type); > + if (IS_ERR(mnt)) { > + err = PTR_ERR(mnt); > unregister_filesystem(&devpts_fs_type); > unregister_sysctl_table(table); > + } else { > + devpts_mnt = mnt; > }
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