* include/linux/cgroup.h:566 suspicious rcu_dereference_check() usage!
@ 2012-10-05 22:52 Cristian Rodríguez
2012-10-08 19:49 ` Paul E. McKenney
0 siblings, 1 reply; 5+ messages in thread
From: Cristian Rodríguez @ 2012-10-05 22:52 UTC (permalink / raw)
To: linux-kernel
Hi:
I am getting this in the current linus tree.
[ 0.408781] ===============================
[ 0.408783] [ INFO: suspicious RCU usage. ]
[ 0.408786] 3.6.0-canneverbe-07124-g5f3d2f2 #18 Not tainted
[ 0.408789] -------------------------------
[ 0.408791] include/linux/cgroup.h:566 suspicious
rcu_dereference_check() usage!
[ 0.408795]
[ 0.408795] other info that might help us debug this:
[ 0.408795]
[ 0.408799]
[ 0.408799] rcu_scheduler_active = 1, debug_locks = 0
[ 0.408802] 2 locks held by kdevtmpfs/49:
[ 0.408804] #0: (sb_writers){.+.+.+}, at: [<ffffffff8119a2ef>]
mnt_want_write+0x1f/0x50
[ 0.408814] #1: (&sb->s_type->i_mutex_key#3/1){+.+.+.}, at:
[<ffffffff811857cf>] kern_path_create+0x7f/0x170
[ 0.408822]
[ 0.408822] stack backtrace:
[ 0.408825] Pid: 49, comm: kdevtmpfs Not tainted
3.6.0-canneverbe-07124-g5f3d2f2 #18
[ 0.408829] Call Trace:
[ 0.408834] [<ffffffff8109fabd>] lockdep_rcu_suspicious+0xfd/0x130
[ 0.408838] [<ffffffff812a876d>] devcgroup_inode_mknod+0x18d/0x230
[ 0.408843] [<ffffffff8126f923>] ? security_capable+0x13/0x20
[ 0.408848] [<ffffffff8104a06f>] ? ns_capable+0x3f/0x80
[ 0.408851] [<ffffffff81186c09>] vfs_mknod+0x79/0x140
[ 0.408856] [<ffffffff813a6df2>] handle_create.isra.2+0x72/0x200
[ 0.408860] [<ffffffff813a702c>] ? devtmpfsd+0xac/0x140
[ 0.408863] [<ffffffff813a7094>] devtmpfsd+0x114/0x140
[ 0.408867] [<ffffffff813a6f80>] ? handle_create.isra.2+0x200/0x200
[ 0.408871] [<ffffffff81064de6>] kthread+0xd6/0xe0
[ 0.408877] [<ffffffff81578cb4>] kernel_thread_helper+0x4/0x10
[ 0.408881] [<ffffffff8156f85c>] ? retint_restore_args+0xe/0xe
[ 0.408885] [<ffffffff81064d10>] ? flush_kthread_work+0x190/0x190
[ 0.408889] [<ffffffff81578cb0>] ? gs_change+0xb/0xb
Hope someone can take a look at it.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: include/linux/cgroup.h:566 suspicious rcu_dereference_check() usage!
2012-10-05 22:52 include/linux/cgroup.h:566 suspicious rcu_dereference_check() usage! Cristian Rodríguez
@ 2012-10-08 19:49 ` Paul E. McKenney
2012-10-10 1:08 ` Sergey Senozhatsky
0 siblings, 1 reply; 5+ messages in thread
From: Paul E. McKenney @ 2012-10-08 19:49 UTC (permalink / raw)
To: Cristian Rodríguez; +Cc: linux-kernel
On Fri, Oct 05, 2012 at 07:52:15PM -0300, Cristian Rodríguez wrote:
> Hi:
> I am getting this in the current linus tree.
>
> [ 0.408781] ===============================
> [ 0.408783] [ INFO: suspicious RCU usage. ]
> [ 0.408786] 3.6.0-canneverbe-07124-g5f3d2f2 #18 Not tainted
> [ 0.408789] -------------------------------
> [ 0.408791] include/linux/cgroup.h:566 suspicious
> rcu_dereference_check() usage!
> [ 0.408795]
> [ 0.408795] other info that might help us debug this:
> [ 0.408795]
> [ 0.408799]
> [ 0.408799] rcu_scheduler_active = 1, debug_locks = 0
> [ 0.408802] 2 locks held by kdevtmpfs/49:
> [ 0.408804] #0: (sb_writers){.+.+.+}, at: [<ffffffff8119a2ef>]
> mnt_want_write+0x1f/0x50
> [ 0.408814] #1: (&sb->s_type->i_mutex_key#3/1){+.+.+.}, at:
> [<ffffffff811857cf>] kern_path_create+0x7f/0x170
> [ 0.408822]
> [ 0.408822] stack backtrace:
> [ 0.408825] Pid: 49, comm: kdevtmpfs Not tainted
> 3.6.0-canneverbe-07124-g5f3d2f2 #18
> [ 0.408829] Call Trace:
> [ 0.408834] [<ffffffff8109fabd>] lockdep_rcu_suspicious+0xfd/0x130
> [ 0.408838] [<ffffffff812a876d>] devcgroup_inode_mknod+0x18d/0x230
> [ 0.408843] [<ffffffff8126f923>] ? security_capable+0x13/0x20
> [ 0.408848] [<ffffffff8104a06f>] ? ns_capable+0x3f/0x80
> [ 0.408851] [<ffffffff81186c09>] vfs_mknod+0x79/0x140
> [ 0.408856] [<ffffffff813a6df2>] handle_create.isra.2+0x72/0x200
> [ 0.408860] [<ffffffff813a702c>] ? devtmpfsd+0xac/0x140
> [ 0.408863] [<ffffffff813a7094>] devtmpfsd+0x114/0x140
> [ 0.408867] [<ffffffff813a6f80>] ? handle_create.isra.2+0x200/0x200
> [ 0.408871] [<ffffffff81064de6>] kthread+0xd6/0xe0
> [ 0.408877] [<ffffffff81578cb4>] kernel_thread_helper+0x4/0x10
> [ 0.408881] [<ffffffff8156f85c>] ? retint_restore_args+0xe/0xe
> [ 0.408885] [<ffffffff81064d10>] ? flush_kthread_work+0x190/0x190
> [ 0.408889] [<ffffffff81578cb0>] ? gs_change+0xb/0xb
>
>
> Hope someone can take a look at it.
It looks to me like commit #ad676077 (device_cgroup: convert device_cgroup
internally to policy + exceptions) removed a needed rcu_read_lock().
See below for an untested patch restoring rcu_read_lock().
Thanx, Paul
------------------------------------------------------------------------
device_cgroup: Restore rcu_read_lock() protection to devcgroup_inode_mknod()
Commit ad676077 (device_cgroup: convert device_cgroup internally to
policy + exceptions) restructured devcgroup_inode_mknod(), removing
rcu_read_lock() in the process. However, RCU read-side protection
is required by the call to task_devcgroup(), so this commit restores
the rcu_read_lock() and rcu_read_unlock().
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
diff --git a/security/device_cgroup.c b/security/device_cgroup.c
index 44dfc41..c686110 100644
--- a/security/device_cgroup.c
+++ b/security/device_cgroup.c
@@ -576,9 +576,12 @@ int __devcgroup_inode_permission(struct inode *inode, int mask)
int devcgroup_inode_mknod(int mode, dev_t dev)
{
- struct dev_cgroup *dev_cgroup = task_devcgroup(current);
+ struct dev_cgroup *dev_cgroup;
+ int ret;
short type;
+ rcu_read_lock();
+ dev_cgroup = task_devcgroup(current);
if (!S_ISBLK(mode) && !S_ISCHR(mode))
return 0;
@@ -587,7 +590,9 @@ int devcgroup_inode_mknod(int mode, dev_t dev)
else
type = DEV_CHAR;
- return __devcgroup_check_permission(dev_cgroup, type, MAJOR(dev),
+ ret = __devcgroup_check_permission(dev_cgroup, type, MAJOR(dev),
MINOR(dev), ACC_MKNOD);
+ rcu_read_unlock();
+ return ret;
}
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: include/linux/cgroup.h:566 suspicious rcu_dereference_check() usage!
2012-10-08 19:49 ` Paul E. McKenney
@ 2012-10-10 1:08 ` Sergey Senozhatsky
2012-10-10 3:25 ` Paul E. McKenney
0 siblings, 1 reply; 5+ messages in thread
From: Sergey Senozhatsky @ 2012-10-10 1:08 UTC (permalink / raw)
To: Paul E. McKenney; +Cc: Cristian Rodríguez, linux-kernel, James Morris
On (10/08/12 12:49), Paul E. McKenney wrote:
>
> ------------------------------------------------------------------------
>
> device_cgroup: Restore rcu_read_lock() protection to devcgroup_inode_mknod()
>
> Commit ad676077 (device_cgroup: convert device_cgroup internally to
> policy + exceptions) restructured devcgroup_inode_mknod(), removing
> rcu_read_lock() in the process. However, RCU read-side protection
> is required by the call to task_devcgroup(), so this commit restores
> the rcu_read_lock() and rcu_read_unlock().
>
> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
>
> diff --git a/security/device_cgroup.c b/security/device_cgroup.c
> index 44dfc41..c686110 100644
> --- a/security/device_cgroup.c
> +++ b/security/device_cgroup.c
> @@ -576,9 +576,12 @@ int __devcgroup_inode_permission(struct inode *inode, int mask)
>
> int devcgroup_inode_mknod(int mode, dev_t dev)
> {
> - struct dev_cgroup *dev_cgroup = task_devcgroup(current);
> + struct dev_cgroup *dev_cgroup;
> + int ret;
> short type;
>
> + rcu_read_lock();
> + dev_cgroup = task_devcgroup(current);
> if (!S_ISBLK(mode) && !S_ISCHR(mode))
> return 0;
>
> @@ -587,7 +590,9 @@ int devcgroup_inode_mknod(int mode, dev_t dev)
> else
> type = DEV_CHAR;
>
> - return __devcgroup_check_permission(dev_cgroup, type, MAJOR(dev),
> + ret = __devcgroup_check_permission(dev_cgroup, type, MAJOR(dev),
> MINOR(dev), ACC_MKNOD);
> + rcu_read_unlock();
> + return ret;
>
> }
>
I believe the same should be done for __devcgroup_inode_permission() as well. And we
probably can call task_devcgroup() and rcu_read_lock() after "S_ISBLK(mode) && !S_ISCHR(mode)"
checks (I guess we also need to unlock RCU on `return 0').
----------------------------------------------------------------------------
Commit ad676077
| Author: Aristeu Rozanski <aris@redhat.com>
| Date: Thu Oct 4 17:15:17 2012 -0700
| device_cgroup: convert device_cgroup internally to policy + exceptions
moved RCU read-side protection from devcgroup_inode_mknod(), which, however is required
by task_devcgroup(). Patch also add RCU read-side protection to __devcgroup_inode_permission()
function, introduced in commit ad676077.
[ 0.946303] include/linux/cgroup.h:566 suspicious rcu_dereference_check() usage!
[ 0.946511]
[ 0.946606] 2 locks held by kdevtmpfs/28:
[ 0.946684] #0: (sb_writers){.+.+.+}, at: [<ffffffff81144bcb>] mnt_want_write+0x24/0x4b
[ 0.947083] #1: (&sb->s_type->i_mutex_key#3/1){+.+.+.}, at: [<ffffffff81133d04>] kern_path_create+0x83/0x144
[ 0.947598]
[ 0.947787] Call Trace:
[ 0.947868] [<ffffffff81089644>] lockdep_rcu_suspicious+0x109/0x112
[ 0.947958] [<ffffffff81258fa0>] devcgroup_inode_mknod+0x9e/0xee
[ 0.948043] [<ffffffff81132ee7>] vfs_mknod+0x8a/0xed
[ 0.948129] [<ffffffff813b98af>] handle_create.isra.2+0x144/0x1b5
[ 0.948214] [<ffffffff813b99bf>] ? devtmpfsd+0x9f/0x138
[ 0.948298] [<ffffffff81295d5c>] ? do_raw_spin_lock+0x67/0xde
[ 0.948384] [<ffffffff81295e92>] ? do_raw_spin_unlock+0x8f/0x98
[ 0.948469] [<ffffffff813b9920>] ? handle_create.isra.2+0x1b5/0x1b5
[ 0.948554] [<ffffffff813b9a04>] devtmpfsd+0xe4/0x138
[ 0.948638] [<ffffffff813b9920>] ? handle_create.isra.2+0x1b5/0x1b5
[ 0.948724] [<ffffffff810582b6>] kthread+0xd5/0xdd
[ 0.948814] [<ffffffff814db664>] kernel_thread_helper+0x4/0x10
[ 0.948900] [<ffffffff814d2973>] ? retint_restore_args+0x13/0x13
[ 0.948985] [<ffffffff810581e1>] ? __init_kthread_worker+0x5a/0x5a
[ 0.949069] [<ffffffff814db660>] ? gs_change+0x13/0x13
devcgroup_inode_mknod() part submitted by Paul E. McKenney.
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
---
security/device_cgroup.c | 21 +++++++++++++++++----
1 file changed, 17 insertions(+), 4 deletions(-)
diff --git a/security/device_cgroup.c b/security/device_cgroup.c
index 44dfc41..043eb00 100644
--- a/security/device_cgroup.c
+++ b/security/device_cgroup.c
@@ -558,7 +558,8 @@ static int __devcgroup_check_permission(struct dev_cgroup *dev_cgroup,
int __devcgroup_inode_permission(struct inode *inode, int mask)
{
- struct dev_cgroup *dev_cgroup = task_devcgroup(current);
+ struct dev_cgroup *dev_cgroup;
+ int ret;
short type, access = 0;
if (S_ISBLK(inode->i_mode))
@@ -570,13 +571,20 @@ int __devcgroup_inode_permission(struct inode *inode, int mask)
if (mask & MAY_READ)
access |= ACC_READ;
- return __devcgroup_check_permission(dev_cgroup, type, imajor(inode),
+ rcu_read_lock();
+
+ dev_cgroup = task_devcgroup(current);
+ ret = __devcgroup_check_permission(dev_cgroup, type, imajor(inode),
iminor(inode), access);
+
+ rcu_read_unlock();
+ return ret;
}
int devcgroup_inode_mknod(int mode, dev_t dev)
{
- struct dev_cgroup *dev_cgroup = task_devcgroup(current);
+ struct dev_cgroup *dev_cgroup;
+ int ret;
short type;
if (!S_ISBLK(mode) && !S_ISCHR(mode))
@@ -587,7 +595,12 @@ int devcgroup_inode_mknod(int mode, dev_t dev)
else
type = DEV_CHAR;
- return __devcgroup_check_permission(dev_cgroup, type, MAJOR(dev),
+ rcu_read_lock();
+
+ dev_cgroup = task_devcgroup(current);
+ ret = __devcgroup_check_permission(dev_cgroup, type, MAJOR(dev),
MINOR(dev), ACC_MKNOD);
+ rcu_read_unlock();
+ return ret;
}
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: include/linux/cgroup.h:566 suspicious rcu_dereference_check() usage!
2012-10-10 1:08 ` Sergey Senozhatsky
@ 2012-10-10 3:25 ` Paul E. McKenney
2012-10-10 23:20 ` Sergey Senozhatsky
0 siblings, 1 reply; 5+ messages in thread
From: Paul E. McKenney @ 2012-10-10 3:25 UTC (permalink / raw)
To: Sergey Senozhatsky; +Cc: Cristian Rodríguez, linux-kernel, James Morris
On Tue, Oct 09, 2012 at 06:08:59PM -0700, Sergey Senozhatsky wrote:
> On (10/08/12 12:49), Paul E. McKenney wrote:
> >
> > ------------------------------------------------------------------------
> >
> > device_cgroup: Restore rcu_read_lock() protection to devcgroup_inode_mknod()
> >
> > Commit ad676077 (device_cgroup: convert device_cgroup internally to
> > policy + exceptions) restructured devcgroup_inode_mknod(), removing
> > rcu_read_lock() in the process. However, RCU read-side protection
> > is required by the call to task_devcgroup(), so this commit restores
> > the rcu_read_lock() and rcu_read_unlock().
> >
> > Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> >
> > diff --git a/security/device_cgroup.c b/security/device_cgroup.c
> > index 44dfc41..c686110 100644
> > --- a/security/device_cgroup.c
> > +++ b/security/device_cgroup.c
> > @@ -576,9 +576,12 @@ int __devcgroup_inode_permission(struct inode *inode, int mask)
> >
> > int devcgroup_inode_mknod(int mode, dev_t dev)
> > {
> > - struct dev_cgroup *dev_cgroup = task_devcgroup(current);
> > + struct dev_cgroup *dev_cgroup;
> > + int ret;
> > short type;
> >
> > + rcu_read_lock();
> > + dev_cgroup = task_devcgroup(current);
> > if (!S_ISBLK(mode) && !S_ISCHR(mode))
> > return 0;
> >
> > @@ -587,7 +590,9 @@ int devcgroup_inode_mknod(int mode, dev_t dev)
> > else
> > type = DEV_CHAR;
> >
> > - return __devcgroup_check_permission(dev_cgroup, type, MAJOR(dev),
> > + ret = __devcgroup_check_permission(dev_cgroup, type, MAJOR(dev),
> > MINOR(dev), ACC_MKNOD);
> > + rcu_read_unlock();
> > + return ret;
> >
> > }
> >
>
>
> I believe the same should be done for __devcgroup_inode_permission() as well. And we
> probably can call task_devcgroup() and rcu_read_lock() after "S_ISBLK(mode) && !S_ISCHR(mode)"
> checks (I guess we also need to unlock RCU on `return 0').
Looks sane to me! Dropping my patch.
Thanx, Paul
> ----------------------------------------------------------------------------
>
> Commit ad676077
> | Author: Aristeu Rozanski <aris@redhat.com>
> | Date: Thu Oct 4 17:15:17 2012 -0700
> | device_cgroup: convert device_cgroup internally to policy + exceptions
>
> moved RCU read-side protection from devcgroup_inode_mknod(), which, however is required
> by task_devcgroup(). Patch also add RCU read-side protection to __devcgroup_inode_permission()
> function, introduced in commit ad676077.
>
> [ 0.946303] include/linux/cgroup.h:566 suspicious rcu_dereference_check() usage!
> [ 0.946511]
> [ 0.946606] 2 locks held by kdevtmpfs/28:
> [ 0.946684] #0: (sb_writers){.+.+.+}, at: [<ffffffff81144bcb>] mnt_want_write+0x24/0x4b
> [ 0.947083] #1: (&sb->s_type->i_mutex_key#3/1){+.+.+.}, at: [<ffffffff81133d04>] kern_path_create+0x83/0x144
> [ 0.947598]
> [ 0.947787] Call Trace:
> [ 0.947868] [<ffffffff81089644>] lockdep_rcu_suspicious+0x109/0x112
> [ 0.947958] [<ffffffff81258fa0>] devcgroup_inode_mknod+0x9e/0xee
> [ 0.948043] [<ffffffff81132ee7>] vfs_mknod+0x8a/0xed
> [ 0.948129] [<ffffffff813b98af>] handle_create.isra.2+0x144/0x1b5
> [ 0.948214] [<ffffffff813b99bf>] ? devtmpfsd+0x9f/0x138
> [ 0.948298] [<ffffffff81295d5c>] ? do_raw_spin_lock+0x67/0xde
> [ 0.948384] [<ffffffff81295e92>] ? do_raw_spin_unlock+0x8f/0x98
> [ 0.948469] [<ffffffff813b9920>] ? handle_create.isra.2+0x1b5/0x1b5
> [ 0.948554] [<ffffffff813b9a04>] devtmpfsd+0xe4/0x138
> [ 0.948638] [<ffffffff813b9920>] ? handle_create.isra.2+0x1b5/0x1b5
> [ 0.948724] [<ffffffff810582b6>] kthread+0xd5/0xdd
> [ 0.948814] [<ffffffff814db664>] kernel_thread_helper+0x4/0x10
> [ 0.948900] [<ffffffff814d2973>] ? retint_restore_args+0x13/0x13
> [ 0.948985] [<ffffffff810581e1>] ? __init_kthread_worker+0x5a/0x5a
> [ 0.949069] [<ffffffff814db660>] ? gs_change+0x13/0x13
>
>
> devcgroup_inode_mknod() part submitted by Paul E. McKenney.
>
>
> Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
>
> ---
>
> security/device_cgroup.c | 21 +++++++++++++++++----
> 1 file changed, 17 insertions(+), 4 deletions(-)
>
> diff --git a/security/device_cgroup.c b/security/device_cgroup.c
> index 44dfc41..043eb00 100644
> --- a/security/device_cgroup.c
> +++ b/security/device_cgroup.c
> @@ -558,7 +558,8 @@ static int __devcgroup_check_permission(struct dev_cgroup *dev_cgroup,
>
> int __devcgroup_inode_permission(struct inode *inode, int mask)
> {
> - struct dev_cgroup *dev_cgroup = task_devcgroup(current);
> + struct dev_cgroup *dev_cgroup;
> + int ret;
> short type, access = 0;
>
> if (S_ISBLK(inode->i_mode))
> @@ -570,13 +571,20 @@ int __devcgroup_inode_permission(struct inode *inode, int mask)
> if (mask & MAY_READ)
> access |= ACC_READ;
>
> - return __devcgroup_check_permission(dev_cgroup, type, imajor(inode),
> + rcu_read_lock();
> +
> + dev_cgroup = task_devcgroup(current);
> + ret = __devcgroup_check_permission(dev_cgroup, type, imajor(inode),
> iminor(inode), access);
> +
> + rcu_read_unlock();
> + return ret;
> }
>
> int devcgroup_inode_mknod(int mode, dev_t dev)
> {
> - struct dev_cgroup *dev_cgroup = task_devcgroup(current);
> + struct dev_cgroup *dev_cgroup;
> + int ret;
> short type;
>
> if (!S_ISBLK(mode) && !S_ISCHR(mode))
> @@ -587,7 +595,12 @@ int devcgroup_inode_mknod(int mode, dev_t dev)
> else
> type = DEV_CHAR;
>
> - return __devcgroup_check_permission(dev_cgroup, type, MAJOR(dev),
> + rcu_read_lock();
> +
> + dev_cgroup = task_devcgroup(current);
> + ret = __devcgroup_check_permission(dev_cgroup, type, MAJOR(dev),
> MINOR(dev), ACC_MKNOD);
>
> + rcu_read_unlock();
> + return ret;
> }
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: include/linux/cgroup.h:566 suspicious rcu_dereference_check() usage!
2012-10-10 3:25 ` Paul E. McKenney
@ 2012-10-10 23:20 ` Sergey Senozhatsky
0 siblings, 0 replies; 5+ messages in thread
From: Sergey Senozhatsky @ 2012-10-10 23:20 UTC (permalink / raw)
To: Paul E. McKenney
Cc: Sergey Senozhatsky, Cristian Rodríguez, linux-kernel,
James Morris
On (10/09/12 20:25), Paul E. McKenney wrote:
>
> Looks sane to me! Dropping my patch.
>
> Thanx, Paul
>
Thanks a lot, Paul. I will resend with proper subject, so it'll be more visible in the list.
-ss
> > ----------------------------------------------------------------------------
> >
> > Commit ad676077
> > | Author: Aristeu Rozanski <aris@redhat.com>
> > | Date: Thu Oct 4 17:15:17 2012 -0700
> > | device_cgroup: convert device_cgroup internally to policy + exceptions
> >
> > moved RCU read-side protection from devcgroup_inode_mknod(), which, however is required
> > by task_devcgroup(). Patch also add RCU read-side protection to __devcgroup_inode_permission()
> > function, introduced in commit ad676077.
> >
> > [ 0.946303] include/linux/cgroup.h:566 suspicious rcu_dereference_check() usage!
> > [ 0.946511]
> > [ 0.946606] 2 locks held by kdevtmpfs/28:
> > [ 0.946684] #0: (sb_writers){.+.+.+}, at: [<ffffffff81144bcb>] mnt_want_write+0x24/0x4b
> > [ 0.947083] #1: (&sb->s_type->i_mutex_key#3/1){+.+.+.}, at: [<ffffffff81133d04>] kern_path_create+0x83/0x144
> > [ 0.947598]
> > [ 0.947787] Call Trace:
> > [ 0.947868] [<ffffffff81089644>] lockdep_rcu_suspicious+0x109/0x112
> > [ 0.947958] [<ffffffff81258fa0>] devcgroup_inode_mknod+0x9e/0xee
> > [ 0.948043] [<ffffffff81132ee7>] vfs_mknod+0x8a/0xed
> > [ 0.948129] [<ffffffff813b98af>] handle_create.isra.2+0x144/0x1b5
> > [ 0.948214] [<ffffffff813b99bf>] ? devtmpfsd+0x9f/0x138
> > [ 0.948298] [<ffffffff81295d5c>] ? do_raw_spin_lock+0x67/0xde
> > [ 0.948384] [<ffffffff81295e92>] ? do_raw_spin_unlock+0x8f/0x98
> > [ 0.948469] [<ffffffff813b9920>] ? handle_create.isra.2+0x1b5/0x1b5
> > [ 0.948554] [<ffffffff813b9a04>] devtmpfsd+0xe4/0x138
> > [ 0.948638] [<ffffffff813b9920>] ? handle_create.isra.2+0x1b5/0x1b5
> > [ 0.948724] [<ffffffff810582b6>] kthread+0xd5/0xdd
> > [ 0.948814] [<ffffffff814db664>] kernel_thread_helper+0x4/0x10
> > [ 0.948900] [<ffffffff814d2973>] ? retint_restore_args+0x13/0x13
> > [ 0.948985] [<ffffffff810581e1>] ? __init_kthread_worker+0x5a/0x5a
> > [ 0.949069] [<ffffffff814db660>] ? gs_change+0x13/0x13
> >
> >
> > devcgroup_inode_mknod() part submitted by Paul E. McKenney.
> >
> >
> > Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
> >
> > ---
> >
> > security/device_cgroup.c | 21 +++++++++++++++++----
> > 1 file changed, 17 insertions(+), 4 deletions(-)
> >
> > diff --git a/security/device_cgroup.c b/security/device_cgroup.c
> > index 44dfc41..043eb00 100644
> > --- a/security/device_cgroup.c
> > +++ b/security/device_cgroup.c
> > @@ -558,7 +558,8 @@ static int __devcgroup_check_permission(struct dev_cgroup *dev_cgroup,
> >
> > int __devcgroup_inode_permission(struct inode *inode, int mask)
> > {
> > - struct dev_cgroup *dev_cgroup = task_devcgroup(current);
> > + struct dev_cgroup *dev_cgroup;
> > + int ret;
> > short type, access = 0;
> >
> > if (S_ISBLK(inode->i_mode))
> > @@ -570,13 +571,20 @@ int __devcgroup_inode_permission(struct inode *inode, int mask)
> > if (mask & MAY_READ)
> > access |= ACC_READ;
> >
> > - return __devcgroup_check_permission(dev_cgroup, type, imajor(inode),
> > + rcu_read_lock();
> > +
> > + dev_cgroup = task_devcgroup(current);
> > + ret = __devcgroup_check_permission(dev_cgroup, type, imajor(inode),
> > iminor(inode), access);
> > +
> > + rcu_read_unlock();
> > + return ret;
> > }
> >
> > int devcgroup_inode_mknod(int mode, dev_t dev)
> > {
> > - struct dev_cgroup *dev_cgroup = task_devcgroup(current);
> > + struct dev_cgroup *dev_cgroup;
> > + int ret;
> > short type;
> >
> > if (!S_ISBLK(mode) && !S_ISCHR(mode))
> > @@ -587,7 +595,12 @@ int devcgroup_inode_mknod(int mode, dev_t dev)
> > else
> > type = DEV_CHAR;
> >
> > - return __devcgroup_check_permission(dev_cgroup, type, MAJOR(dev),
> > + rcu_read_lock();
> > +
> > + dev_cgroup = task_devcgroup(current);
> > + ret = __devcgroup_check_permission(dev_cgroup, type, MAJOR(dev),
> > MINOR(dev), ACC_MKNOD);
> >
> > + rcu_read_unlock();
> > + return ret;
> > }
> >
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at http://vger.kernel.org/majordomo-info.html
> > Please read the FAQ at http://www.tux.org/lkml/
> >
>
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2012-10-10 23:23 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2012-10-05 22:52 include/linux/cgroup.h:566 suspicious rcu_dereference_check() usage! Cristian Rodríguez
2012-10-08 19:49 ` Paul E. McKenney
2012-10-10 1:08 ` Sergey Senozhatsky
2012-10-10 3:25 ` Paul E. McKenney
2012-10-10 23:20 ` Sergey Senozhatsky
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox