4.1-stable review patch. If anyone has any objections, please let me know.
------------------
From: Jeff Layton <jlayton@xxxxxxxxxxxxxxx>
commit a24221dca1868101c9b4b5adde4a6a5b1a3a64a7 upstream.
If we have two tasks racing to update a mirror's credentials, then they
can end up leaking one (or more) sets of credentials. The first task
will set mirror->cred and then the second task will just overwrite it.
Use a cmpxchg to ensure that the creds are only set once. If we get to
the point where we would set mirror->cred and find that they're already
set, then we just release the creds that were just found.
Signed-off-by: Jeff Layton <jeff.layton@xxxxxxxxxxxxxxx>
Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/nfs/flexfilelayout/flexfilelayoutdev.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/fs/nfs/flexfilelayout/flexfilelayoutdev.c
+++ b/fs/nfs/flexfilelayout/flexfilelayoutdev.c
@@ -324,7 +324,8 @@ static int ff_layout_update_mirror_cred(
__func__, PTR_ERR(cred));
return PTR_ERR(cred);
} else {
- mirror->cred = cred;
+ if (cmpxchg(&mirror->cred, NULL, cred))
+ put_rpccred(cred);
}
}
return 0;
--
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