diff options
| author | Davidlohr Bueso <davidlohr.bueso@hp.com> | 2013-09-11 14:26:23 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-10-18 07:45:47 -0700 |
| commit | bd58e2dc27330012ff1774cd54d41d6e7ffcbc36 (patch) | |
| tree | 0f106d3f82e15fce2c2d2741ac1668247b1d9d6d | |
| parent | 247ec302b53873fa13bbb413b5df982cb5d7f78f (diff) | |
| download | lwn-bd58e2dc27330012ff1774cd54d41d6e7ffcbc36.tar.gz lwn-bd58e2dc27330012ff1774cd54d41d6e7ffcbc36.zip | |
ipc,shm: shorten critical region for shmat
commit c2c737a0461e61a34676bd0bd1bc1a70a1b4e396 upstream.
Similar to other system calls, acquire the kern_ipc_perm lock after doing
the initial permission and security checks.
[sasha.levin@oracle.com: dont leave do_shmat with rcu lock held]
Signed-off-by: Davidlohr Bueso <davidlohr.bueso@hp.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | ipc/shm.c | 14 |
1 files changed, 10 insertions, 4 deletions
diff --git a/ipc/shm.c b/ipc/shm.c index 1eeef9f48154..9cd876451626 100644 --- a/ipc/shm.c +++ b/ipc/shm.c @@ -19,6 +19,9 @@ * namespaces support * OpenVZ, SWsoft Inc. * Pavel Emelianov <xemul@openvz.org> + * + * Better ipc lock (kern_ipc_perm.lock) handling + * Davidlohr Bueso <davidlohr.bueso@hp.com>, June 2013. */ #include <linux/slab.h> @@ -1086,10 +1089,11 @@ long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr, * additional creator id... */ ns = current->nsproxy->ipc_ns; - shp = shm_lock_check(ns, shmid); + rcu_read_lock(); + shp = shm_obtain_object_check(ns, shmid); if (IS_ERR(shp)) { err = PTR_ERR(shp); - goto out; + goto out_unlock; } err = -EACCES; @@ -1100,11 +1104,13 @@ long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr, if (err) goto out_unlock; + ipc_lock_object(&shp->shm_perm); path = shp->shm_file->f_path; path_get(&path); shp->shm_nattch++; size = i_size_read(path.dentry->d_inode); - shm_unlock(shp); + ipc_unlock_object(&shp->shm_perm); + rcu_read_unlock(); err = -ENOMEM; sfd = kzalloc(sizeof(*sfd), GFP_KERNEL); @@ -1175,7 +1181,7 @@ out_nattch: return err; out_unlock: - shm_unlock(shp); + rcu_read_unlock(); out: return err; } |