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authorManfred Spraul <manfred@colorfullife.com>2018-08-21 22:01:21 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-08-22 10:52:51 -0700
commit615c999cd8a07b7c3c93bbdee89ef705d2ce52e1 (patch)
tree9a61d371b17498dead9ff9136ebd25402bab82fa /ipc
parent5cb366bb3a746f6b06ea086b322e21e345401c9d (diff)
downloadlinux-stericsson-615c999cd8a07b7c3c93bbdee89ef705d2ce52e1.tar.gz
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@syzkaller.appspotmail.com: syzbot found an issue with kern_ipc_perm.seq Link: http://lkml.kernel.org/r/20180712185241.4017-2-manfred@colorfullife.com Signed-off-by: Manfred Spraul <manfred@colorfullife.com> Reviewed-by: Davidlohr Bueso <dbueso@suse.de> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Kees Cook <keescook@chromium.org> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'ipc')
-rw-r--r--ipc/msg.c19
-rw-r--r--ipc/sem.c18
-rw-r--r--ipc/shm.c19
3 files changed, 41 insertions, 15 deletions
diff --git a/ipc/msg.c b/ipc/msg.c
index 203281198079..7cb89a9b24e2 100644
--- a/ipc/msg.c
+++ b/ipc/msg.c
@@ -492,7 +492,6 @@ static int msgctl_stat(struct ipc_namespace *ns, int msqid,
int cmd, struct msqid64_ds *p)
{
struct msg_queue *msq;
- int id = 0;
int err;
memset(p, 0, sizeof(*p));
@@ -504,7 +503,6 @@ static int msgctl_stat(struct ipc_namespace *ns, int msqid,
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)) {
@@ -549,10 +547,21 @@ static int msgctl_stat(struct ipc_namespace *ns, int msqid,
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 --git a/ipc/sem.c b/ipc/sem.c
index 00ef2f743a62..18e50f464f76 100644
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -1223,7 +1223,6 @@ static int semctl_stat(struct ipc_namespace *ns, int semid,
{
struct sem_array *sma;
time64_t semotime;
- int id = 0;
int err;
memset(semid64, 0, sizeof(*semid64));
@@ -1235,7 +1234,6 @@ static int semctl_stat(struct ipc_namespace *ns, int semid,
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)) {
@@ -1275,10 +1273,20 @@ static int semctl_stat(struct ipc_namespace *ns, int semid,
#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 --git a/ipc/shm.c b/ipc/shm.c
index b204feb38274..b3b089315d3b 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -962,7 +962,6 @@ static int shmctl_stat(struct ipc_namespace *ns, int shmid,
int cmd, struct shmid64_ds *tbuf)
{
struct shmid_kernel *shp;
- int id = 0;
int err;
memset(tbuf, 0, sizeof(*tbuf));
@@ -974,7 +973,6 @@ static int shmctl_stat(struct ipc_namespace *ns, int shmid,
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)) {
@@ -1024,10 +1022,21 @@ static int shmctl_stat(struct ipc_namespace *ns, int shmid,
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;