[PATCH 1/5] sound/isa/opti9xx/miro.c: eliminate possible double free

From: Julia Lawall
Date: Sun Oct 21 2012 - 06:53:19 EST

From: Julia Lawall <Julia.Lawall@xxxxxxx>

snd_miro_probe is a static function that is only called twice in the file
that defines it. At each call site, its argument is freed using
snd_card_free. Thus, there is no need for snd_miro_probe to call
snd_card_free on its argument on any of its error exit paths.

Because snd_card_free both reads the fields of its argument and kfrees its
argments, the results of the second snd_card_free should be unpredictable.

A simplified version of the semantic match that finds this problem is as
follows: (http://coccinelle.lip6.fr/)

// <smpl>
identifier f,free,a;
parameter list[n] ps;
type T;
expression e;

f(ps,T a,...) {
... when any
when != a = e
if(...) { ... free(a); ... return ...; }
... when any

identifier r.f,r.free;
expression x,a;
expression list[r.n] xs;

* x = f(xs,a,...);
if (...) { ... free(a); ... return ...; }
// </smpl>

Signed-off-by: Julia Lawall <Julia.Lawall@xxxxxxx>

Not tested.

sound/isa/opti9xx/miro.c | 1 -
1 file changed, 1 deletion(-)

diff --git a/sound/isa/opti9xx/miro.c b/sound/isa/opti9xx/miro.c
index 3d1afb6..4a7ff4e 100644
--- a/sound/isa/opti9xx/miro.c
+++ b/sound/isa/opti9xx/miro.c
@@ -1286,7 +1286,6 @@ static int __devinit snd_miro_probe(struct snd_card *card)

error = snd_card_miro_aci_detect(card, miro);
if (error < 0) {
- snd_card_free(card);
snd_printk(KERN_ERR "unable to detect aci chip\n");
return -ENODEV;

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/