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Subject[PATCH 6/6] drivers/net/pppol2tp.c: remove null pointer dereference
From: Julia Lawall <julia@diku.dk>

If session is NULL, it is not possible to access its name field. So I have
split apart the printing of the error message to drop the printing of the
name field in this case.


This problem was found using the following semantic match
(http://www.emn.fr/x-info/coccinelle/)

// <smpl>
@@
expression E, E1;
identifier f;
statement S1,S2,S3;
@@

* if (E == NULL)
{
... when != if (E == NULL) S1 else S2
when != E = E1
* E->f
... when any
return ...;
}
else S3
// </smpl>
Signed-off-by: Julia Lawall <julia@diku.dk>

---
diff -u -p a/drivers/net/pppol2tp.c b/drivers/net/pppol2tp.c
--- linux-2.6/drivers/net/pppol2tp.c 2008-05-09 16:46:57.000000000 +0200
+++ linuxcopy/drivers/net/pppol2tp.c 2008-05-12 15:30:52.000000000 +0200
@@ -1621,9 +1621,16 @@ out_no_ppp:
end:
release_sock(sk);

- if (error != 0)
- PRINTK(session ? session->debug : -1, PPPOL2TP_MSG_CONTROL, KERN_WARNING,
- "%s: connect failed: %d\n", session->name, error);
+ if (error != 0) {
+ if (session)
+ PRINTK(session->debug,
+ PPPOL2TP_MSG_CONTROL, KERN_WARNING,
+ "%s: connect failed: %d\n",
+ session->name, error);
+ else
+ PRINTK(-1, PPPOL2TP_MSG_CONTROL, KERN_WARNING,
+ "connect failed: %d\n", error);
+ }

return error;
}

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