Messages in this thread Patch in this message | | | From | Davidlohr Bueso <> | Subject | [PATCH 08/11] ipc,shm: shorten critical region for shmat | Date | Tue, 18 Jun 2013 18:18:33 -0700 |
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Similar to other system calls, acquire the kern_ipc_perm lock after doing the initial permission and security checks.
Signed-off-by: Davidlohr Bueso <davidlohr.bueso@hp.com> --- ipc/shm.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/ipc/shm.c b/ipc/shm.c index d1b3ebf..2fe6170 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> @@ -1086,7 +1089,8 @@ 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; @@ -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; } -- 1.7.11.7
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