Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=cbfb50e6e2e9c580848c0f51d37c24cdfb1cb704
Commit:     cbfb50e6e2e9c580848c0f51d37c24cdfb1cb704
Parent:     839041329fd3410e07d614f81e75bb43367d8f89
Author:     Roland Dreier <[EMAIL PROTECTED]>
AuthorDate: Fri Oct 19 20:01:43 2007 -0700
Committer:  Roland Dreier <[EMAIL PROTECTED]>
CommitDate: Fri Oct 19 20:01:43 2007 -0700

    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 <[EMAIL PROTECTED]>
    Signed-off-by: Roland Dreier <[EMAIL PROTECTED]>
---
 drivers/infiniband/core/uverbs_cmd.c |    8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/infiniband/core/uverbs_cmd.c 
b/drivers/infiniband/core/uverbs_cmd.c
index 01d7008..495c803 100644
--- a/drivers/infiniband/core/uverbs_cmd.c
+++ b/drivers/infiniband/core/uverbs_cmd.c
@@ -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;
-
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