The patch titled
Subject: ipc: compute kern_ipc_perm.id under the ipc lock
has been added to the -mm tree. Its filename is
ipc-ipc-compute-kern_ipc_permid-under-the-ipc-lock.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/ipc-ipc-compute-kern_ipc_permid-under-the-ipc-lock.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/ipc-ipc-compute-kern_ipc_permid-under-the-ipc-lock.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>
Subject: ipc: compute kern_ipc_perm.id under the ipc lock
ipc_addid() initializes kern_ipc_perm.id after having called
ipc_idr_alloc().
Thus a parallel semctl() or msgctl() that uses e.g. MSG_STAT may use this
unitialized value as the return code.
The patch moves all accesses to kern_ipc_perm.id under the spin_lock().
The issues is related to the finding of
syzbot+2827ef6b3385deb07eaf@xxxxxxxxxxxxxxxxxxxxxxxxx: syzbot found an
issue with kern_ipc_perm.seq
Link: http://lkml.kernel.org/r/20180712185241.4017-2-manfred@xxxxxxxxxxxxxxxx
Signed-off-by: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>
Reviewed-by: Davidlohr Bueso <dbueso@xxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Davidlohr Bueso <dave@xxxxxxxxxxxx>
Cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Cc: Michael Kerrisk <mtk.manpages@xxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
diff -puN ipc/msg.c~ipc-ipc-compute-kern_ipc_permid-under-the-ipc-lock ipc/msg.c
--- a/ipc/msg.c~ipc-ipc-compute-kern_ipc_permid-under-the-ipc-lock
+++ a/ipc/msg.c
@@ -491,7 +491,6 @@ static int msgctl_stat(struct ipc_namesp
int cmd, struct msqid64_ds *p)
{
struct msg_queue *msq;
- int id = 0;
int err;
memset(p, 0, sizeof(*p));
@@ -503,7 +502,6 @@ static int msgctl_stat(struct ipc_namesp
err = PTR_ERR(msq);
goto out_unlock;
}
- id = msq->q_perm.id;
} else { /* IPC_STAT */
msq = msq_obtain_object_check(ns, msqid);
if (IS_ERR(msq)) {
@@ -548,10 +546,21 @@ static int msgctl_stat(struct ipc_namesp
p->msg_lspid = pid_vnr(msq->q_lspid);
p->msg_lrpid = pid_vnr(msq->q_lrpid);
- ipc_unlock_object(&msq->q_perm);
- rcu_read_unlock();
- return id;
+ if (cmd == IPC_STAT) {
+ /*
+ * As defined in SUS:
+ * Return 0 on success
+ */
+ err = 0;
+ } else {
+ /*
+ * MSG_STAT and MSG_STAT_ANY (both Linux specific)
+ * Return the full id, including the sequence number
+ */
+ err = msq->q_perm.id;
+ }
+ ipc_unlock_object(&msq->q_perm);
out_unlock:
rcu_read_unlock();
return err;
diff -puN ipc/sem.c~ipc-ipc-compute-kern_ipc_permid-under-the-ipc-lock ipc/sem.c
--- a/ipc/sem.c~ipc-ipc-compute-kern_ipc_permid-under-the-ipc-lock
+++ a/ipc/sem.c
@@ -1222,7 +1222,6 @@ static int semctl_stat(struct ipc_namesp
{
struct sem_array *sma;
time64_t semotime;
- int id = 0;
int err;
memset(semid64, 0, sizeof(*semid64));
@@ -1234,7 +1233,6 @@ static int semctl_stat(struct ipc_namesp
err = PTR_ERR(sma);
goto out_unlock;
}
- id = sma->sem_perm.id;
} else { /* IPC_STAT */
sma = sem_obtain_object_check(ns, semid);
if (IS_ERR(sma)) {
@@ -1274,10 +1272,20 @@ static int semctl_stat(struct ipc_namesp
#endif
semid64->sem_nsems = sma->sem_nsems;
+ if (cmd == IPC_STAT) {
+ /*
+ * As defined in SUS:
+ * Return 0 on success
+ */
+ err = 0;
+ } else {
+ /*
+ * SEM_STAT and SEM_STAT_ANY (both Linux specific)
+ * Return the full id, including the sequence number
+ */
+ err = sma->sem_perm.id;
+ }
ipc_unlock_object(&sma->sem_perm);
- rcu_read_unlock();
- return id;
-
out_unlock:
rcu_read_unlock();
return err;
diff -puN ipc/shm.c~ipc-ipc-compute-kern_ipc_permid-under-the-ipc-lock ipc/shm.c
--- a/ipc/shm.c~ipc-ipc-compute-kern_ipc_permid-under-the-ipc-lock
+++ a/ipc/shm.c
@@ -949,7 +949,6 @@ static int shmctl_stat(struct ipc_namesp
int cmd, struct shmid64_ds *tbuf)
{
struct shmid_kernel *shp;
- int id = 0;
int err;
memset(tbuf, 0, sizeof(*tbuf));
@@ -961,7 +960,6 @@ static int shmctl_stat(struct ipc_namesp
err = PTR_ERR(shp);
goto out_unlock;
}
- id = shp->shm_perm.id;
} else { /* IPC_STAT */
shp = shm_obtain_object_check(ns, shmid);
if (IS_ERR(shp)) {
@@ -1011,10 +1009,21 @@ static int shmctl_stat(struct ipc_namesp
tbuf->shm_lpid = pid_vnr(shp->shm_lprid);
tbuf->shm_nattch = shp->shm_nattch;
- ipc_unlock_object(&shp->shm_perm);
- rcu_read_unlock();
- return id;
+ if (cmd == IPC_STAT) {
+ /*
+ * As defined in SUS:
+ * Return 0 on success
+ */
+ err = 0;
+ } else {
+ /*
+ * SHM_STAT and SHM_STAT_ANY (both Linux specific)
+ * Return the full id, including the sequence number
+ */
+ err = shp->shm_perm.id;
+ }
+ ipc_unlock_object(&shp->shm_perm);
out_unlock:
rcu_read_unlock();
return err;
_
Patches currently in -mm which might be from manfred@xxxxxxxxxxxxxxxx are
ipc-ipc-compute-kern_ipc_permid-under-the-ipc-lock.patch
ipc-reorganize-initialization-of-kern_ipc_permseq.patch
ipc-utilc-use-ipc_rcu_putref-for-failues-in-ipc_addid.patch
ipc-rename-ipcctl_pre_down_nolock.patch
ipc-utilc-correct-comment-in-ipc_obtain_object_check.patch
ipc-utilc-further-variable-name-cleanups.patch
ipc-utilc-update-return-value-of-ipc_getref-from-int-to-bool.patch
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