2.6.32-longterm review patch. If anyone has any objections, please let me know.
------------------
commit e8577d1f0329d4842e8302e289fb2c22156abef4 upstream.
ipc_addid() makes a new ipc identifier visible to everyone. New objects
start as locked, so that the caller can complete the initialization
after the call. Within struct sem_array, at least sma->sem_base and
sma->sem_nsems are accessed without any locks, therefore this approach
doesn't work.
Thus: Move the ipc_addid() to the end of the initialization.
Signed-off-by: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>
Reported-by: Rik van Riel <riel@xxxxxxxxxx>
Acked-by: Rik van Riel <riel@xxxxxxxxxx>
Acked-by: Davidlohr Bueso <dave@xxxxxxxxxxxx>
Acked-by: Rafael Aquini <aquini@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
[bwh: Backported to 2.6.32:
- Adjust context
- The error path being moved looks a little different]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Signed-off-by: Willy Tarreau <w@xxxxxx>
---
ipc/sem.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
diff --git a/ipc/sem.c b/ipc/sem.c
index b781007..26dc5b1 100644
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -264,6 +264,12 @@ static int newary(struct ipc_namespace *ns, struct ipc_params *params)
return retval;
}
+ sma->sem_base = (struct sem *) &sma[1];
+ INIT_LIST_HEAD(&sma->sem_pending);
+ INIT_LIST_HEAD(&sma->list_id);
+ sma->sem_nsems = nsems;
+ sma->sem_ctime = get_seconds();
+
id = ipc_addid(&sem_ids(ns), &sma->sem_perm, ns->sc_semmni);
if (id < 0) {
security_sem_free(sma);
@@ -272,11 +278,6 @@ static int newary(struct ipc_namespace *ns, struct ipc_params *params)
}
ns->used_sems += nsems;
- sma->sem_base = (struct sem *) &sma[1];
- INIT_LIST_HEAD(&sma->sem_pending);
- INIT_LIST_HEAD(&sma->list_id);
- sma->sem_nsems = nsems;
- sma->sem_ctime = get_seconds();
sem_unlock(sma);
return sma->sem_perm.id;
--
1.7.12.2.21.g234cd45.dirty
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