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media: ddbridge: fix teardown/deregistration order in ddb_input_detach()
Brought to attention by Matthias Schwarzott <zzam@gentoo.org> 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@gentoo.org> Signed-off-by: Daniel Scheller <d.scheller@gmx.net> Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
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1 changed files with 6 additions and 5 deletions
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@ -1255,11 +1255,6 @@ static void dvb_input_detach(struct ddb_input *input)
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switch (dvb->attached) {
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case 0x31:
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client = dvb->i2c_client[0];
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if (client) {
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module_put(client->dev.driver->owner);
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i2c_unregister_device(client);
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}
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if (dvb->fe2)
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dvb_unregister_frontend(dvb->fe2);
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if (dvb->fe)
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@ -1273,6 +1268,12 @@ static void dvb_input_detach(struct ddb_input *input)
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dvb->fe = dvb->fe2 = NULL;
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/* fallthrough */
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case 0x20:
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client = dvb->i2c_client[0];
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if (client) {
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module_put(client->dev.driver->owner);
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i2c_unregister_device(client);
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}
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dvb_net_release(&dvb->dvbnet);
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/* fallthrough */
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case 0x12:
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