Eric Lee / smarc-ti-linux-kernel

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Commit 19dfd03af7f194adb7ecfc3c2ecfefc1b6686ef1

Authored by Davidlohr Bueso
Committed by Greg Kroah-Hartman
1 parent dbb563ec7b

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>

Showing 1 changed file with 10 additions and 4 deletions Side-by-side Diff

... ... @@ -19,6 +19,9 @@
19 19 * namespaces support
20 20 * OpenVZ, SWsoft Inc.
21 21 * Pavel Emelianov <xemul@openvz.org>
  22 + *
  23 + * Better ipc lock (kern_ipc_perm.lock) handling
  24 + * Davidlohr Bueso <davidlohr.bueso@hp.com>, June 2013.
22 25 */
23 26  
24 27 #include <linux/slab.h>
25 28  
... ... @@ -1093,10 +1096,11 @@
1093 1096 * additional creator id...
1094 1097 */
1095 1098 ns = current->nsproxy->ipc_ns;
1096   - shp = shm_lock_check(ns, shmid);
  1099 + rcu_read_lock();
  1100 + shp = shm_obtain_object_check(ns, shmid);
1097 1101 if (IS_ERR(shp)) {
1098 1102 err = PTR_ERR(shp);
1099   - goto out;
  1103 + goto out_unlock;
1100 1104 }
1101 1105  
1102 1106 err = -EACCES;
1103 1107  
... ... @@ -1107,11 +1111,13 @@
1107 1111 if (err)
1108 1112 goto out_unlock;
1109 1113  
  1114 + ipc_lock_object(&shp->shm_perm);
1110 1115 path = shp->shm_file->f_path;
1111 1116 path_get(&path);
1112 1117 shp->shm_nattch++;
1113 1118 size = i_size_read(path.dentry->d_inode);
1114   - shm_unlock(shp);
  1119 + ipc_unlock_object(&shp->shm_perm);
  1120 + rcu_read_unlock();
1115 1121  
1116 1122 err = -ENOMEM;
1117 1123 sfd = kzalloc(sizeof(*sfd), GFP_KERNEL);
... ... @@ -1182,7 +1188,7 @@
1182 1188 return err;
1183 1189  
1184 1190 out_unlock:
1185   - shm_unlock(shp);
  1191 + rcu_read_unlock();
1186 1192 out:
1187 1193 return err;
1188 1194 }