diff options
| author | Jiri Slaby <jslaby@suse.cz> | 2012-10-26 00:37:34 +0400 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-10-26 01:37:52 +0400 |
| commit | 8c9506d16925f1b1314d93af383ca3134eb534d8 (patch) | |
| tree | e14dbc5816b375463b8d37eda0f79bcd0ea96a3b /security | |
| parent | ef5d437f71afdf4afdbab99213add99f4b1318fd (diff) | |
| download | linux-8c9506d16925f1b1314d93af383ca3134eb534d8.tar.xz | |
cgroup: fix invalid rcu dereference
Commit ad676077a2ae ("device_cgroup: convert device_cgroup internally to
policy + exceptions") removed rcu locks which are needed in
task_devcgroup called in this chain:
devcgroup_inode_mknod OR __devcgroup_inode_permission ->
__devcgroup_inode_permission ->
task_devcgroup ->
task_subsys_state ->
task_subsys_state_check.
Change the code so that task_devcgroup is safely called with rcu read
lock held.
===============================
[ INFO: suspicious RCU usage. ]
3.6.0-rc5-next-20120913+ #42 Not tainted
-------------------------------
include/linux/cgroup.h:553 suspicious rcu_dereference_check() usage!
other info that might help us debug this:
rcu_scheduler_active = 1, debug_locks = 0
2 locks held by kdevtmpfs/23:
#0: (sb_writers){.+.+.+}, at: [<ffffffff8116873f>]
mnt_want_write+0x1f/0x50
#1: (&sb->s_type->i_mutex_key#3/1){+.+.+.}, at: [<ffffffff811558af>]
kern_path_create+0x7f/0x170
stack backtrace:
Pid: 23, comm: kdevtmpfs Not tainted 3.6.0-rc5-next-20120913+ #42
Call Trace:
lockdep_rcu_suspicious+0xfd/0x130
devcgroup_inode_mknod+0x19d/0x240
vfs_mknod+0x71/0xf0
handle_create.isra.2+0x72/0x200
devtmpfsd+0x114/0x140
? handle_create.isra.2+0x200/0x200
kthread+0xd6/0xe0
kernel_thread_helper+0x4/0x10
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Dave Jones <davej@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Li Zefan <lizefan@huawei.com>
Cc: James Morris <jmorris@namei.org>
Cc: Pavel Emelyanov <xemul@openvz.org>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'security')
| -rw-r--r-- | security/device_cgroup.c | 15 |
1 files changed, 7 insertions, 8 deletions
diff --git a/security/device_cgroup.c b/security/device_cgroup.c index 44dfc415a379..46d01fcc0d15 100644 --- a/security/device_cgroup.c +++ b/security/device_cgroup.c @@ -533,10 +533,10 @@ struct cgroup_subsys devices_subsys = { * * returns 0 on success, -EPERM case the operation is not permitted */ -static int __devcgroup_check_permission(struct dev_cgroup *dev_cgroup, - short type, u32 major, u32 minor, +static int __devcgroup_check_permission(short type, u32 major, u32 minor, short access) { + struct dev_cgroup *dev_cgroup; struct dev_exception_item ex; int rc; @@ -547,6 +547,7 @@ static int __devcgroup_check_permission(struct dev_cgroup *dev_cgroup, ex.access = access; rcu_read_lock(); + dev_cgroup = task_devcgroup(current); rc = may_access(dev_cgroup, &ex); rcu_read_unlock(); @@ -558,7 +559,6 @@ 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); short type, access = 0; if (S_ISBLK(inode->i_mode)) @@ -570,13 +570,12 @@ 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), - iminor(inode), access); + return __devcgroup_check_permission(type, imajor(inode), iminor(inode), + access); } int devcgroup_inode_mknod(int mode, dev_t dev) { - struct dev_cgroup *dev_cgroup = task_devcgroup(current); short type; if (!S_ISBLK(mode) && !S_ISCHR(mode)) @@ -587,7 +586,7 @@ int devcgroup_inode_mknod(int mode, dev_t dev) else type = DEV_CHAR; - return __devcgroup_check_permission(dev_cgroup, type, MAJOR(dev), - MINOR(dev), ACC_MKNOD); + return __devcgroup_check_permission(type, MAJOR(dev), MINOR(dev), + ACC_MKNOD); } |