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| author | Rafael Aquini <aquini@redhat.com> | 2014-01-27 17:07:01 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-01-27 21:02:39 -0800 |
| commit | 0f3d2b0135f4bdbfe47a99753923a64efd373d11 (patch) | |
| tree | 4b211b7502e2412aedd94400bdcb012a2b5814b3 /ipc/msg.c | |
| parent | 78f5009cc35eb5e52d276a046d90ee2f41b60f8c (diff) | |
| download | lwn-0f3d2b0135f4bdbfe47a99753923a64efd373d11.tar.gz lwn-0f3d2b0135f4bdbfe47a99753923a64efd373d11.zip | |
ipc: introduce ipc_valid_object() helper to sort out IPC_RMID races
After the locking semantics for the SysV IPC API got improved, a couple
of IPC_RMID race windows were opened because we ended up dropping the
'kern_ipc_perm.deleted' check performed way down in ipc_lock(). The
spotted races got sorted out by re-introducing the old test within the
racy critical sections.
This patch introduces ipc_valid_object() to consolidate the way we cope
with IPC_RMID races by using the same abstraction across the API
implementation.
Signed-off-by: Rafael Aquini <aquini@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Greg Thelen <gthelen@google.com>
Reviewed-by: Davidlohr Bueso <davidlohr@hp.com>
Cc: Manfred Spraul <manfred@colorfullife.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 | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/ipc/msg.c b/ipc/msg.c index 558aa91186b6..8983ea57d970 100644 --- a/ipc/msg.c +++ b/ipc/msg.c @@ -696,7 +696,7 @@ long do_msgsnd(int msqid, long mtype, void __user *mtext, goto out_unlock0; /* raced with RMID? */ - if (msq->q_perm.deleted) { + if (!ipc_valid_object(&msq->q_perm)) { err = -EIDRM; goto out_unlock0; } @@ -731,7 +731,8 @@ long do_msgsnd(int msqid, long mtype, void __user *mtext, ipc_lock_object(&msq->q_perm); ipc_rcu_putref(msq, ipc_rcu_free); - if (msq->q_perm.deleted) { + /* raced with RMID? */ + if (!ipc_valid_object(&msq->q_perm)) { err = -EIDRM; goto out_unlock0; } @@ -909,7 +910,7 @@ long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp, int msgfl ipc_lock_object(&msq->q_perm); /* raced with RMID? */ - if (msq->q_perm.deleted) { + if (!ipc_valid_object(&msq->q_perm)) { msg = ERR_PTR(-EIDRM); goto out_unlock0; } |