diff options
| author | Manfred Spraul <manfred@colorfullife.com> | 2018-08-21 22:01:21 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2018-08-22 10:52:51 -0700 |
| commit | 615c999cd8a07b7c3c93bbdee89ef705d2ce52e1 (patch) | |
| tree | 9a61d371b17498dead9ff9136ebd25402bab82fa /ipc/msg.c | |
| parent | 5cb366bb3a746f6b06ea086b322e21e345401c9d (diff) | |
| download | lwn-615c999cd8a07b7c3c93bbdee89ef705d2ce52e1.tar.gz lwn-615c999cd8a07b7c3c93bbdee89ef705d2ce52e1.zip | |
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/msg.c')
| -rw-r--r-- | ipc/msg.c | 19 |
1 files changed, 14 insertions, 5 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; |