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@xxxxxx>
---
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@xxxxxxxxxx>
+ *
+ * Better ipc lock (kern_ipc_perm.lock) handling
+ * Davidlohr Bueso <davidlohr.bueso@xxxxxx>, 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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