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  1. 05 May, 2016 1 commit
    • Eric W. Biederman's avatar
      propogate_mnt: Handle the first propogated copy being a slave · 5ec0811d
      Eric W. Biederman authored 
      When the first propgated copy was a slave the following oops would result:
> BUG: unable to handle kernel NULL pointer dereference at 0000000000000010
> IP: [<ffffffff811fba4e>] propagate_one+0xbe/0x1c0
> PGD bacd4067 PUD bac66067 PMD 0
> Oops: 0000 [#1] SMP
> Modules linked in:
> CPU: 1 PID: 824 Comm: mount Not tainted 4.6.0-rc5userns+ #1523
> Hardware name: Bochs Bochs, BIOS Bochs 01/01/2007
> task: ffff8800bb0a8000 ti: ffff8800bac3c000 task.ti: ffff8800bac3c000
> RIP: 0010:[<ffffffff811fba4e>]  [<ffffffff811fba4e>] propagate_one+0xbe/0x1c0
> RSP: 0018:ffff8800bac3fd38  EFLAGS: 00010283
> RAX: 0000000000000000 RBX: ffff8800bb77ec00 RCX: 0000000000000010
> RDX: 0000000000000000 RSI: ffff8800bb58c000 RDI: ffff8800bb58c480
> RBP: ffff8800bac3fd48 R08: 0000000000000001 R09: 0000000000000000
> R10: 0000000000001ca1 R11: 0000000000001c9d R12: 0000000000000000
> R13: ffff8800ba713800 R14: ffff8800bac3fda0 R15: ffff8800bb77ec00
> FS:  00007f3c0cd9b7e0(0000) GS:ffff8800bfb00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000000000010 CR3: 00000000bb79d000 CR4: 00000000000006e0
> Stack:
>  ffff8800bb77ec00 0000000000000000 ffff8800bac3fd88 ffffffff811fbf85
>  ffff8800bac3fd98 ffff8800bb77f080 ffff8800ba713800 ffff8800bb262b40
>  0000000000000000 0000000000000000 ffff8800bac3fdd8 ffffffff811f1da0
> Call Trace:
>  [<ffffffff811fbf85>] propagate_mnt+0x105/0x140
>  [<ffffffff811f1da0>] attach_recursive_mnt+0x120/0x1e0
>  [<ffffffff811f1ec3>] graft_tree+0x63/0x70
>  [<ffffffff811f1f6b>] do_add_mount+0x9b/0x100
>  [<ffffffff811f2c1a>] do_mount+0x2aa/0xdf0
>  [<ffffffff8117efbe>] ? strndup_user+0x4e/0x70
>  [<ffffffff811f3a45>] SyS_mount+0x75/0xc0
>  [<ffffffff8100242b>] do_syscall_64+0x4b/0xa0
>  [<ffffffff81988f3c>] entry_SYSCALL64_slow_path+0x25/0x25
> Code: 00 00 75 ec 48 89 0d 02 22 22 01 8b 89 10 01 00 00 48 89 05 fd 21 22 01 39 8e 10 01 00 00 0f 84 e0 00 00 00 48 8b 80 d8 00 00 00 <48> 8b 50 10 48 89 05 df 21 22 01 48 89 15 d0 21 22 01 8b 53 30
> RIP  [<ffffffff811fba4e>] propagate_one+0xbe/0x1c0
>  RSP <ffff8800bac3fd38>
> CR2: 0000000000000010
> ---[ end trace 2725ecd95164f217 ]---

This oops happens with the namespace_sem held and can be triggered by
non-root users.  An all around not pleasant experience.

To avoid this scenario when finding the appropriate source mount to
copy stop the walk up the mnt_master chain when the first source mount
is encountered.

Further rewrite the walk up the last_source mnt_master chain so that
it is clear what is going on.

The reason why the first source mount is special is that it it's
mnt_parent is not a mount in the dest_mnt propagation tree, and as
such termination conditions based up on the dest_mnt mount propgation
tree do not make sense.

To avoid other kinds of confusion last_dest is not changed when
computing last_source.  last_dest is only used once in propagate_one
and that is above the point of the code being modified, so changing
the global variable is meaningless and confusing.

Cc: stable@vger.kernel.org
fixes: f2ebb3a9 ("smarter propagate_mnt()")
Reported-by: default avatarTycho Andersen <tycho.andersen@canonical.com>
Reviewed-by: default avatarSeth Forshee <seth.forshee@canonical.com>
Tested-by: default avatarSeth Forshee <seth.forshee@canonical.com>
Signed-off-by: default avatar"Eric W. Biederman" <ebiederm@xmission.com>
      5ec0811d
  3. 24 Apr, 2016 2 commits
  5. 23 Apr, 2016 10 commits
  7. 22 Apr, 2016 24 commits
  9. 21 Apr, 2016 3 commits
    • cpaul@redhat.com's avatar
      drm/dp/mst: Validate port in drm_dp_payload_send_msg() · deba0a2a
      cpaul@redhat.com authored 
      With the joys of things running concurrently, there's always a chance
that the port we get passed in drm_dp_payload_send_msg() isn't actually
valid anymore. Because of this, we need to make sure we validate the
reference to the port before we use it otherwise we risk running into
various race conditions. For instance, on the Dell MST monitor I have
here for testing, hotplugging it enough times causes us to kernel panic:

[drm:intel_mst_enable_dp] 1
[drm:drm_dp_update_payload_part2] payload 0 1
[drm:intel_get_hpd_pins] hotplug event received, stat 0x00200000, dig 0x10101011, pins 0x00000020
[drm:intel_hpd_irq_handler] digital hpd port B - short
[drm:intel_dp_hpd_pulse] got hpd irq on port B - short
[drm:intel_dp_check_mst_status] got esi 00 10 00
[drm:drm_dp_update_payload_part2] payload 1 1
general protection fault: 0000 [#1] SMP
…
Call Trace:
 [<ffffffffa012b632>] drm_dp_update_payload_part2+0xc2/0x130 [drm_kms_helper]
 [<ffffffffa032ef08>] intel_mst_enable_dp+0xf8/0x180 [i915]
 [<ffffffffa0310dbd>] haswell_crtc_enable+0x3ed/0x8c0 [i915]
 [<ffffffffa030c84d>] intel_atomic_commit+0x5ad/0x1590 [i915]
 [<ffffffffa01db877>] ? drm_atomic_set_crtc_for_connector+0x57/0xe0 [drm]
 [<ffffffffa01dc4e7>] drm_atomic_commit+0x37/0x60 [drm]
 [<ffffffffa0130a3a>] drm_atomic_helper_set_config+0x7a/0xb0 [drm_kms_helper]
 [<ffffffffa01cc482>] drm_mode_set_config_internal+0x62/0x100 [drm]
 [<ffffffffa01d02ad>] drm_mode_setcrtc+0x3cd/0x4e0 [drm]
 [<ffffffffa01c18e3>] drm_ioctl+0x143/0x510 [drm]
 [<ffffffffa01cfee0>] ? drm_mode_setplane+0x1b0/0x1b0 [drm]
 [<ffffffff810f79a7>] ? hrtimer_start_range_ns+0x1b7/0x3a0
 [<ffffffff81212962>] do_vfs_ioctl+0x92/0x570
 [<ffffffff81590852>] ? __sys_recvmsg+0x42/0x80
 [<ffffffff81212eb9>] SyS_ioctl+0x79/0x90
 [<ffffffff816b4e32>] entry_SYSCALL_64_fastpath+0x1a/0xa4
RIP  [<ffffffffa012b026>] drm_dp_payload_send_msg+0x146/0x1f0 [drm_kms_helper]

Which occurs because of the hotplug event shown in the log, which ends
up causing DRM's dp helpers to drop the port we're updating the payload
on and panic.

CC: stable@vger.kernel.org
Signed-off-by: default avatarLyude <cpaul@redhat.com>
Reviewed-by: default avatarDavid Airlie <airlied@linux.ie>
Signed-off-by: default avatarDave Airlie <airlied@redhat.com>
      deba0a2a
    • Dave Airlie's avatar
      Merge branch 'linux-4.6' of git://github.com/skeggsb/linux into drm-fixes · 3addc4e3
      Dave Airlie authored 
      Single nouveau regression fix
* 'linux-4.6' of git://github.com/skeggsb/linux:
  drm/nouveau/kms: fix setting of default values for dithering properties
      3addc4e3
    • Ben Skeggs's avatar
      drm/nouveau/kms: fix setting of default values for dithering properties · 38bdcfc1
      Ben Skeggs authored 
      Signed-off-by: default avatarBen Skeggs <bskeggs@redhat.com>
      38bdcfc1
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