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From: Ahmad Fatoum <a.fatoum@pengutronix.de>
To: barebox@lists.infradead.org
Cc: Holger Assmann <has@pengutronix.de>,
	Ahmad Fatoum <a.fatoum@pengutronix.de>
Subject: [PATCH master v2] nv: fix use-after-free when clearing from shell
Date: Thu, 12 Nov 2020 18:25:24 +0100	[thread overview]
Message-ID: <20201112172524.1293-1-a.fatoum@pengutronix.de> (raw)

When we use hush to set the same nv.var twice to the empty string:

  $ nv.user=
  $ nv.user=

nv_set is called twice with a NULL val argument leading
to a double free and accompanied memory corruption.

Reorder the code, so p->value is freed just once.

Fixes: fa4c41ba60af ("nvvar: when setting a nvvar to NULL just free the content")
Cc: Holger Assmann <has@pengutronix.de>
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
v1 -> v2:
  Use correct author email in DCO
---
 common/globalvar.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/common/globalvar.c b/common/globalvar.c
index 60793d7a30c6..a55b38b00fd5 100644
--- a/common/globalvar.c
+++ b/common/globalvar.c
@@ -179,16 +179,12 @@ static int nv_set(struct device_d *dev, struct param_d *p, const char *name, con
 {
 	int ret;
 
-	if (!val) {
-		if (p)
-			free(p->value);
-		return 0;
+	if (val) {
+		ret = dev_set_param(&global_device, name, val);
+		if (ret)
+			return ret;
 	}
 
-	ret = dev_set_param(&global_device, name, val);
-	if (ret)
-		return ret;
-
 	if (p) {
 		free(p->value);
 		p->value = xstrdup(val);
-- 
2.28.0


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             reply	other threads:[~2020-11-12 17:25 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-12 17:25 Ahmad Fatoum [this message]
2020-11-13  7:37 ` Sascha Hauer

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