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IB/uverbs: Fix checking of userspace object ownership 

Commit 9ead190b ("IB/uverbs: Don't serialize with ib_uverbs_idr_mutex")
rewrote how userspace objects are looked up in the uverbs module's
idrs, and introduced a severe bug in the process: there is no checking
that an operation is being performed by the right process any more.
Fix this by adding the missing check of uobj->context in __idr_get_uobj().

Apparently everyone is being very careful to only touch their own
objects, because this bug was introduced in June 2006 in 2.6.18, and
has gone undetected until now.

Cc: stable <stable@kernel.org>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
This commit is contained in:
Roland Dreier 2007-10-19 20:01:43 -07:00
parent 839041329f
commit cbfb50e6e2
1 changed files with 6 additions and 2 deletions
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8
drivers/infiniband/core/uverbs_cmd.c
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@ -147,8 +147,12 @@ static struct ib_uobject *__idr_get_uobj(struct idr *idr, int id,
spin_lock(&ib_uverbs_idr_lock);
uobj = idr_find(idr, id);
if (uobj)
kref_get(&uobj->ref);
if (uobj) {
if (uobj->context == context)
kref_get(&uobj->ref);
else
uobj = NULL;
}
spin_unlock(&ib_uverbs_idr_lock);
return uobj;