Re: [Patch] Possible dereference in fs/nfsd/nfs4callback.c

From: Chuck Lever
Date: Tue Sep 26 2006 - 09:08:48 EST

Eric Sesterhenn wrote:

the following commit introduced a possible NULL pointer dereference;a=commitdiff;h=ae5c79476f36512d1100e162606bb5691f2cce5a

we set cb->cb_client to NULL and pass it to rpc_shutdown_client() which dereferences it.

What was I thinking/smoking? ;-)

The easy fix below.

Signed-off-by: Eric Sesterhenn <snakebyte@xxxxxx>

--- linux-2.6.18-git5/fs/nfsd/nfs4callback.c.orig 2006-09-26 12:24:23.000000000 +0200
+++ linux-2.6.18-git5/fs/nfsd/nfs4callback.c 2006-09-26 12:24:40.000000000 +0200
@@ -450,7 +450,8 @@ out_rpciod:
cb->cb_client = NULL;
- rpc_shutdown_client(cb->cb_client);
+ if (cb->cb_client)
+ rpc_shutdown_client(cb->cb_client);
dprintk("NFSD: warning: no callback path to client %.*s\n",
(int)clp->cl_name.len, clp->;

Actually I see another problem here.

rpc_create() doesn't return NULL, it returns an ERR_PTR. So the return code check in the code just before this is also bogus.

I'll send a complete fix through Trond.
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