Messages in this thread | | | Date | Wed, 13 Feb 2013 15:37:18 +0100 | From | Marc Kleine-Budde <> | Subject | Re: SELinux + ubifs: possible circular locking dependency |
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On 02/13/2013 01:47 PM, Artem Bityutskiy wrote: >> I'm on a arm imx28 v3.8-rc6 (+ a handfull of patches to support the >> custom board) but no modifications on ubifs, selinux or the vfs layer. >> And not including the xattr patches by Subodh Nijsure. >> >> When booting with SELinux and lockdep enabled I see this _possible_ >> circular locking dependency: > > I guess one needs to really understand how lockdep works, because it > seems there is no direct 'tnc_mutex -> isec->lock', and lockdep somehow > deducts this connection inderectly. > > However, it seems I see what _may_ be the reason, and here is a patch > which I think may fix the issue. Would you please test/review it? It is > inlined and also attached.
Thanks,
[...]
The compiler complains
security/selinux/hooks.c:210:2: error: incompatible type for argument 3 of 'lockdep_init_map' In file included from include/linux/spinlock_types.h:18:0, from include/linux/spinlock.h:81, from include/linux/seqlock.h:29, from include/linux/time.h:5, from include/uapi/linux/timex.h:56, from include/linux/timex.h:56, from include/linux/sched.h:17, from include/linux/tracehook.h:49, from security/selinux/hooks.c:29: include/linux/lockdep.h:279:13: note: expected 'struct lock_class_key *' but argument is of type 'struct lock_class_key'
> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c > index ef26e96..328180e 100644 > --- a/security/selinux/hooks.c > +++ b/security/selinux/hooks.c > @@ -207,6 +207,7 @@ static int inode_alloc_security(struct inode *inode) > return -ENOMEM; > > mutex_init(&isec->lock); > + lockdep_set_class(&isec->lock, inode->i_sb->s_type->i_mutex_key);
So I added an "&", so that the line looks like that:
+ lockdep_set_class(&isec->lock, &inode->i_sb->s_type->i_mutex_key);
> INIT_LIST_HEAD(&isec->list); > isec->inode = inode; > isec->sid = SECINITSID_UNLABELED; >
That solves original circular lock warning, but brings these two:
> [ 0.213843] ------------[ cut here ]------------ > [ 0.218687] WARNING: at kernel/lockdep.c:702 __lock_acquire+0x1824/0x1c58() > [ 0.225875] Modules linked in: > [ 0.229156] [<c000d0f0>] (unwind_backtrace+0x0/0xf0) from [<c001575c>] (warn_slowpath_common+0x4c/0x64) > [ 0.238812] [<c001575c>] (warn_slowpath_common+0x4c/0x64) from [<c0015790>] (warn_slowpath_null+0x1c/0x24) > [ 0.248750] [<c0015790>] (warn_slowpath_null+0x1c/0x24) from [<c00548f0>] (__lock_acquire+0x1824/0x1c58) > [ 0.258500] [<c00548f0>] (__lock_acquire+0x1824/0x1c58) from [<c0055210>] (lock_acquire+0x88/0x9c) > [ 0.267750] [<c0055210>] (lock_acquire+0x88/0x9c) from [<c0390aa4>] (mutex_lock_nested+0x5c/0x2ec) > [ 0.276968] [<c0390aa4>] (mutex_lock_nested+0x5c/0x2ec) from [<c00dcf04>] (lock_mount+0x1c/0xbc) > [ 0.286031] [<c00dcf04>] (lock_mount+0x1c/0xbc) from [<c00dd310>] (do_add_mount+0x18/0xc8) > [ 0.294531] [<c00dd310>] (do_add_mount+0x18/0xc8) from [<c00de17c>] (do_mount+0x1cc/0x8d0) > [ 0.303062] [<c00de17c>] (do_mount+0x1cc/0x8d0) from [<c00de904>] (sys_mount+0x84/0xb8) > [ 0.311343] [<c00de904>] (sys_mount+0x84/0xb8) from [<c022cf58>] (devtmpfsd+0x4c/0x2b8) > [ 0.319593] [<c022cf58>] (devtmpfsd+0x4c/0x2b8) from [<c0034a58>] (kthread+0xa4/0xb0) > [ 0.327656] [<c0034a58>] (kthread+0xa4/0xb0) from [<c0009448>] (ret_from_fork+0x14/0x2c) > [ 0.336062] ---[ end trace 1b75b31a2719ed1c ]---
The warning comes from:
list_for_each_entry(class, hash_head, hash_entry) { if (class->key == key) { /* * Huh! same key, different name? Did someone trample * on some memory? We're most confused. */ WARN_ON_ONCE(class->name != lock->name); return class; } }
[...]
> [ 0.342000] devtmpfs: initialized > [ 0.350187] pinctrl core: initialized pinctrl subsystem > [ 0.358000] > [ 0.359656] ============================================= > [ 0.365218] [ INFO: possible recursive locking detected ] > [ 0.370812] 3.8.0-rc7-00011-g7a589e1-dirty #108 Tainted: G W > [ 0.377562] --------------------------------------------- > [ 0.383125] swapper/1 is trying to acquire lock: > [ 0.387906] (&inode->i_sb->s_type->i_mutex_key#7){+.+.+.}, at: [<c01a988c>] inode_doinit_with_dentry+0x8c/0x55c > [ 0.398437] > [ 0.398437] but task is already holding lock: > [ 0.404562] (&inode->i_sb->s_type->i_mutex_key#7){+.+.+.}, at: [<c0191bd4>] __create_file+0x50/0x25c > [ 0.414093] > [ 0.414093] other info that might help us debug this: > [ 0.420906] Possible unsafe locking scenario: > [ 0.420906] > [ 0.427125] CPU0 > [ 0.429687] ---- > [ 0.432250] lock(&inode->i_sb->s_type->i_mutex_key#7); > [ 0.437781] lock(&inode->i_sb->s_type->i_mutex_key#7); > [ 0.443312] > [ 0.443312] *** DEADLOCK *** > [ 0.443312] > [ 0.449593] May be due to missing lock nesting notation > [ 0.449593] > [ 0.456687] 1 lock held by swapper/1: > [ 0.460500] #0: (&inode->i_sb->s_type->i_mutex_key#7){+.+.+.}, at: [<c0191bd4>] __create_file+0x50/0x25c > [ 0.470468] > [ 0.470468] stack backtrace: > [ 0.475125] [<c000d0f0>] (unwind_backtrace+0x0/0xf0) from [<c0054578>] (__lock_acquire+0x14ac/0x1c58) > [ 0.484625] [<c0054578>] (__lock_acquire+0x14ac/0x1c58) from [<c0055210>] (lock_acquire+0x88/0x9c) > [ 0.493843] [<c0055210>] (lock_acquire+0x88/0x9c) from [<c0390aa4>] (mutex_lock_nested+0x5c/0x2ec) > [ 0.503093] [<c0390aa4>] (mutex_lock_nested+0x5c/0x2ec) from [<c01a988c>] (inode_doinit_with_dentry+0x8c/0x55c) > [ 0.513468] [<c01a988c>] (inode_doinit_with_dentry+0x8c/0x55c) from [<c01a3f9c>] (security_d_instantiate+0x1c/0x34) > [ 0.524187] [<c01a3f9c>] (security_d_instantiate+0x1c/0x34) from [<c0191af0>] (debugfs_mknod.part.15.constprop.18+0x94/0x128) > [ 0.535812] [<c0191af0>] (debugfs_mknod.part.15.constprop.18+0x94/0x128) from [<c0191d34>] (__create_file+0x1b0/0x25c) > [ 0.546781] [<c0191d34>] (__create_file+0x1b0/0x25c) from [<c0191e68>] (debugfs_create_dir+0x1c/0x28) > [ 0.556312] [<c0191e68>] (debugfs_create_dir+0x1c/0x28) from [<c04d1f58>] (pinctrl_init+0x1c/0xd0) > [ 0.565531] [<c04d1f58>] (pinctrl_init+0x1c/0xd0) from [<c0008900>] (do_one_initcall+0x108/0x17c) > [ 0.574656] [<c0008900>] (do_one_initcall+0x108/0x17c) from [<c04c3858>] (kernel_init_freeable+0xec/0x1b4) > [ 0.584593] [<c04c3858>] (kernel_init_freeable+0xec/0x1b4) from [<c0389af0>] (kernel_init+0x8/0xe4) > [ 0.593906] [<c0389af0>] (kernel_init+0x8/0xe4) from [<c0009448>] (ret_from_fork+0x14/0x2c)
Marc -- Pengutronix e.K. | Marc Kleine-Budde | Industrial Linux Solutions | Phone: +49-231-2826-924 | Vertretung West/Dortmund | Fax: +49-5121-206917-5555 | Amtsgericht Hildesheim, HRA 2686 | http://www.pengutronix.de |
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