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authorDavidlohr Bueso <davidlohr.bueso@hp.com>2013-09-11 14:26:23 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-09-11 15:59:42 -0700
commitc2c737a0461e61a34676bd0bd1bc1a70a1b4e396 (patch)
treef8d9d21cbc43ac12a67bbc428cab083adb31cd30 /ipc
parentf42569b1388b1408b574a5e93a23a663647d4181 (diff)
downloadlinux-c2c737a0461e61a34676bd0bd1bc1a70a1b4e396.tar.gz
ipc,shm: shorten critical region for shmat
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>
Diffstat (limited to 'ipc')
-rw-r--r--ipc/shm.c14
1 files changed, 10 insertions, 4 deletions
diff --git a/ipc/shm.c b/ipc/shm.c
index 115dccebc63..28d19f4ece4 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;
}