This is a note to let you know that I've just added the patch titled
ipc,shm: shorten critical region for shmat
to the 3.11-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ipc-shm-shorten-critical-region-for-shmat.patch
and it can be found in the queue-3.11 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From c2c737a0461e61a34676bd0bd1bc1a70a1b4e396 Mon Sep 17 00:00:00 2001
From: Davidlohr Bueso <[email protected]>
Date: Wed, 11 Sep 2013 14:26:23 -0700
Subject: ipc,shm: shorten critical region for shmat
From: Davidlohr Bueso <[email protected]>
commit c2c737a0461e61a34676bd0bd1bc1a70a1b4e396 upstream.
Similar to other system calls, acquire the kern_ipc_perm lock after doing
the initial permission and security checks.
[[email protected]: dont leave do_shmat with rcu lock held]
Signed-off-by: Davidlohr Bueso <[email protected]>
Tested-by: Sedat Dilek <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: Manfred Spraul <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Cc: Mike Galbraith <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
ipc/shm.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -19,6 +19,9 @@
* namespaces support
* OpenVZ, SWsoft Inc.
* Pavel Emelianov <[email protected]>
+ *
+ * Better ipc lock (kern_ipc_perm.lock) handling
+ * Davidlohr Bueso <[email protected]>, June 2013.
*/
#include <linux/slab.h>
@@ -1093,10 +1096,11 @@ long do_shmat(int shmid, char __user *sh
* 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;
@@ -1107,11 +1111,13 @@ long do_shmat(int shmid, char __user *sh
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);
@@ -1182,7 +1188,7 @@ out_nattch:
return err;
out_unlock:
- shm_unlock(shp);
+ rcu_read_unlock();
out:
return err;
}
Patches currently in stable-queue which might be from [email protected] are
queue-3.11/ipc-shm-shorten-critical-region-in-shmctl_down.patch
queue-3.11/ipc-shm-introduce-lockless-functions-to-obtain-the-ipc-object.patch
queue-3.11/ipc-shm-shorten-critical-region-for-shmat.patch
queue-3.11/ipc-shm-shorten-critical-region-for-shmctl.patch
queue-3.11/ipc-shm-introduce-shmctl_nolock.patch
queue-3.11/ipc-drop-ipcctl_pre_down.patch
queue-3.11/ipc-shm-cleanup-do_shmat-pasta.patch
queue-3.11/ipc-shm-make-shmctl_nolock-lockless.patch
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