linux-kernel - [PATCH 2/4] ipc,shm: prevent race with rmid in shmat(2)

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]

Date:	Sun, 15 Sep 2013 20:04:35 -0700
From:	Davidlohr Bueso <davidlohr@...com>
To:	Manfred Spraul <manfred@...orfullife.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Rik van Riel <riel@...hat.com>, Mike Galbraith <efault@....de>,
	sedat.dilek@...il.com,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Davidlohr Bueso <davidlohr@...com>
Subject: [PATCH 2/4] ipc,shm: prevent race with rmid in shmat(2)

This fixes a race in shmat() between finding the msq and
actually attaching the segment, as another thread can delete shmid
underneath us if we are preempted before acquiring the kern_ipc_perm.lock.

Reported-by: Manfred Spraul <manfred@...orfullife.com>
Signed-off-by: Davidlohr Bueso <davidlohr@...com>
---
 ipc/shm.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/ipc/shm.c b/ipc/shm.c
index bc3e897..1afde7e 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -1093,6 +1093,14 @@ long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr,
 		goto out_unlock;
 
 	ipc_lock_object(&shp->shm_perm);
+
+	/* have we raced with RMID? */
+	if (shp->shm_perm.deleted) {
+		err = -EIDRM;
+		ipc_unlock_object(&shp->shm_perm);
+		goto out_unlock;
+	}
+
 	err = security_shm_shmat(shp, shmaddr, shmflg);
 	if (err) {
 		ipc_unlock_object(&shp->shm_perm);
-- 
1.7.11.7

--
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/