* [PATCH]Fix bug in msgrcv/shmat
@ 2001-09-13 20:07 Mingming cao
0 siblings, 0 replies; only message in thread
From: Mingming cao @ 2001-09-13 20:07 UTC (permalink / raw)
To: torvalds, alan; +Cc: linux-kernel, manfreds
Hello, Linux & Alan,
This patch verifies the message queue ID and the shared memory segment
ID for msgrcv and shmat respectively. These IDs consist of a data
structure index value, and a generation number. As data structures are
re-used, the generation number makes it possible to avoid incorrect
data references. The generation numbers are checked via msg_checkid()
and shm_checkid(). The problem is that msgrcv and shmat do not currently
validate the ID. As a result of this, it is possible to reference and
modify the wrong message queue or shared memory segment with the use of
a stale ID.
This patch is against kernel 2.4.9. I tested it and it runs well.
Please apply and CC your comments to me also, thanks.
--
Mingming Cao
IBM Linux Technology Center
diff -urN -X dontdiff linux/ipc/msg.c linux-tk/ipc/msg.c
--- linux/ipc/msg.c Wed Aug 29 18:26:39 2001
+++ linux-tk/ipc/msg.c Wed Aug 29 18:21:42 2001
@@ -742,6 +742,10 @@
if(msq==NULL)
return -EINVAL;
retry:
+ err = -EIDRM;
+ if (msg_checkid(msq,msqid))
+ goto out_unlock;
+
err=-EACCES;
if (ipcperms (&msq->q_perm, S_IRUGO))
goto out_unlock;
diff -urN -X dontdiff linux/ipc/shm.c linux-tk/ipc/shm.c
--- linux/ipc/shm.c Wed Aug 29 18:26:33 2001
+++ linux-tk/ipc/shm.c Wed Aug 29 18:26:15 2001
@@ -606,6 +606,11 @@
shp = shm_lock(shmid);
if(shp == NULL)
return -EINVAL;
+ err = shm_checkid(shp,shmid);
+ if (err) {
+ shm_unlock(shmid);
+ return err;
+ }
if (ipcperms(&shp->shm_perm, acc_mode)) {
shm_unlock(shmid);
return -EACCES;
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2001-09-13 20:07 [PATCH]Fix bug in msgrcv/shmat Mingming cao
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