From: Daniel Scheller <d.scheller@xxxxxxx>
Brought to attention by Matthias Schwarzott <zzam@xxxxxxxxxx> by fixing
possible use-after-free faults in some demod drivers:
In ddb_input_detach(), the i2c_client is unregistered and removed before
dvb frontends are unregistered and detached. While no use-after-free issue
was observed so far, there is another issue with this:
dvb->attached keeps track of the state of the input/output registration,
and the i2c_client unregistration takes place only if everything was
successful (dvb->attached == 0x31). If for some reason an error occurred
during the frontend setup, that value stays at 0x20. In the following
error handling and cleanup, ddb_input_detach() will skip down to that
state, leaving the i2c_client registered, causing refcount issues.
Fix this by moving the i2c_client deregistration down to case 0x20.
Cc: Matthias Schwarzott <zzam@xxxxxxxxxx>
Signed-off-by: Daniel Scheller <d.scheller@xxxxxxx>
---
drivers/media/pci/ddbridge/ddbridge-core.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
diff --git a/drivers/media/pci/ddbridge/ddbridge-core.c b/drivers/media/pci/ddbridge/ddbridge-core.c
index 2464bde1c432..281b6739b0c1 100644
--- a/drivers/media/pci/ddbridge/ddbridge-core.c
+++ b/drivers/media/pci/ddbridge/ddbridge-core.c
@@ -1255,11 +1255,6 @@ static void dvb_input_detach(struct ddb_input *input)
switch (dvb->attached) {
case 0x31:
- client = dvb->i2c_client[0];
- if (client) {
- module_put(client->dev.driver->owner);
- i2c_unregister_device(client);
- }
if (dvb->fe2)
dvb_unregister_frontend(dvb->fe2);
if (dvb->fe)
@@ -1273,6 +1268,12 @@ static void dvb_input_detach(struct ddb_input *input)
dvb->fe = dvb->fe2 = NULL;
/* fallthrough */
case 0x20:
+ client = dvb->i2c_client[0];
+ if (client) {
+ module_put(client->dev.driver->owner);
+ i2c_unregister_device(client);
+ }
+
dvb_net_release(&dvb->dvbnet);
/* fallthrough */
case 0x12:
--
2.13.0
