1. 08 Mar, 2010 2 commits
    • Tejun Heo's avatar
      driver-core: fix race condition in get_device_parent() · 77d3d7c1
      Tejun Heo authored
      sysfs is creating several devices in cuse class concurrently and with
      CONFIG_SYSFS_DEPRECATED turned off, it triggers the following oops.
      
       BUG: unable to handle kernel NULL pointer dereference at 0000000000000038
       IP: [<ffffffff81158b0a>] sysfs_addrm_start+0x4a/0xf0
       PGD 75bb067 PUD 75be067 PMD 0
       Oops: 0000 [#1] PREEMPT SMP
       last sysfs file: /sys/devices/system/cpu/cpu7/topology/core_siblings
       CPU 1
       Modules linked in: cuse fuse
       Pid: 4737, comm: osspd Not tainted 2.6.31-work #77
       RIP: 0010:[<ffffffff81158b0a>]  [<ffffffff81158b0a>] sysfs_addrm_start+0x4a/0xf0
       RSP: 0018:ffff88000042f8f8  EFLAGS: 00010296
       RAX: ffff88000042ffd8 RBX: 0000000000000000 RCX: 0000000000000000
       RDX: 0000000000000000 RSI: ffff880007eef660 RDI: 0000000000000001
       RBP: ffff88000042f918 R08: 0000000000000000 R09: 0000000000000000
       R10: 0000000000000001 R11: ffffffff81158b0a R12: ffff88000042f928
       R13: 00000000fffffff4 R14: 0000000000000000 R15: ffff88000042f9a0
       FS:  00007fe93905a950(0000) GS:ffff880008600000(0000) knlGS:0000000000000000
       CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
       CR2: 0000000000000038 CR3: 00000000077c9000 CR4: 00000000000006e0
       DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
       DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
       Process osspd (pid: 4737, threadinfo ffff88000042e000, task ffff880007eef040)
       Stack:
        ffff880005da10e8 0000000011cc8d6e ffff88000042f928 ffff880003d28a28
       <0> ffff88000042f988 ffffffff811592d7 0000000000000000 0000000000000000
       <0> 0000000000000000 0000000000000000 ffff88000042f958 0000000011cc8d6e
       Call Trace:
        [<ffffffff811592d7>] create_dir+0x67/0xe0
        [<ffffffff811593a8>] sysfs_create_dir+0x58/0xb0
        [<ffffffff8128ca7c>] ? kobject_add_internal+0xcc/0x220
        [<ffffffff812942e1>] ? vsnprintf+0x3c1/0xb90
        [<ffffffff8128cab7>] kobject_add_internal+0x107/0x220
        [<ffffffff8128cd37>] kobject_add_varg+0x47/0x80
        [<ffffffff8128ce53>] kobject_add+0x53/0x90
        [<ffffffff81357d84>] device_add+0xd4/0x690
        [<ffffffff81356c2b>] ? dev_set_name+0x4b/0x70
        [<ffffffffa001a884>] cuse_process_init_reply+0x2b4/0x420 [cuse]
        ...
      
      The problem is that kobject_add_internal() first adds a kobject to the
      kset and then try to create sysfs directory for it.  If the creation
      fails, it remove the kobject from the kset.  get_device_parent()
      accesses class_dirs kset while only holding class_dirs.list_lock to
      see whether the cuse class dir exists.  But when it exists, it may not
      have finished initialization yet or may fail and get removed soon.  In
      the above case, the former happened so the second one ends up trying
      to create subdirectory under NULL sysfs_dirent.
      
      Fix it by grabbing a mutex in get_device_parent().
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Reported-by: default avatarColin Guthrie <cguthrie@mandriva.org>
      Cc: stable <stable@kernel.org>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
      
      77d3d7c1
    • Linus Torvalds's avatar
      Merge git://git.kernel.org/pub/scm/linux/kernel/git/amit/virtio-console · 25cf84cf
      Linus Torvalds authored
      * git://git.kernel.org/pub/scm/linux/kernel/git/amit/virtio-console:
        virtio: console: Use better variable names for fill_queue operation
        virtio: console: Fix type of 'len' as unsigned int
      25cf84cf
  2. 07 Mar, 2010 38 commits