linux-kernel - [ 52/69] ipc,shm: make shmctl

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20131016174319.240084991@linuxfoundation.org>
Date:	Wed, 16 Oct 2013 10:45:01 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Davidlohr Bueso <davidlohr.bueso@...com>,
	Sedat Dilek <sedat.dilek@...il.com>,
	Rik van Riel <riel@...hat.com>,
	Manfred Spraul <manfred@...orfullife.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Mike Galbraith <efault@....de>
Subject: [ 52/69] ipc,shm: make shmctl_nolock lockless

3.10-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Davidlohr Bueso <davidlohr.bueso@...com>

commit c97cb9ccab8c85428ec21eff690642ad2ce1fa8a upstream.

While the INFO cmd doesn't take the ipc lock, the STAT commands do acquire
it unnecessarily.  We can do the permissions and security checks only
holding the rcu lock.

[akpm@...ux-foundation.org: coding-style fixes]
Signed-off-by: Davidlohr Bueso <davidlohr.bueso@...com>
Tested-by: Sedat Dilek <sedat.dilek@...il.com>
Cc: Rik van Riel <riel@...hat.com>
Cc: Manfred Spraul <manfred@...orfullife.com>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Mike Galbraith <efault@....de>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 ipc/shm.c |   19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -882,27 +882,31 @@ static int shmctl_nolock(struct ipc_name
 		struct shmid64_ds tbuf;
 		int result;
 
+		rcu_read_lock();
 		if (cmd == SHM_STAT) {
-			shp = shm_lock(ns, shmid);
+			shp = shm_obtain_object(ns, shmid);
 			if (IS_ERR(shp)) {
 				err = PTR_ERR(shp);
-				goto out;
+				goto out_unlock;
 			}
 			result = shp->shm_perm.id;
 		} else {
-			shp = shm_lock_check(ns, shmid);
+			shp = shm_obtain_object_check(ns, shmid);
 			if (IS_ERR(shp)) {
 				err = PTR_ERR(shp);
-				goto out;
+				goto out_unlock;
 			}
 			result = 0;
 		}
+
 		err = -EACCES;
 		if (ipcperms(ns, &shp->shm_perm, S_IRUGO))
 			goto out_unlock;
+
 		err = security_shm_shmctl(shp, cmd);
 		if (err)
 			goto out_unlock;
+
 		memset(&tbuf, 0, sizeof(tbuf));
 		kernel_to_ipc64_perm(&shp->shm_perm, &tbuf.shm_perm);
 		tbuf.shm_segsz	= shp->shm_segsz;
@@ -912,8 +916,9 @@ static int shmctl_nolock(struct ipc_name
 		tbuf.shm_cpid	= shp->shm_cprid;
 		tbuf.shm_lpid	= shp->shm_lprid;
 		tbuf.shm_nattch	= shp->shm_nattch;
-		shm_unlock(shp);
-		if(copy_shmid_to_user (buf, &tbuf, version))
+		rcu_read_unlock();
+
+		if (copy_shmid_to_user(buf, &tbuf, version))
 			err = -EFAULT;
 		else
 			err = result;
@@ -924,7 +929,7 @@ static int shmctl_nolock(struct ipc_name
 	}
 
 out_unlock:
-	shm_unlock(shp);
+	rcu_read_unlock();
 out:
 	return err;
 }


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/