tree e89225904402f1db8ff54846dad4490938238f46
parent 6b852620fa75d3137929538b4a9aec2f953ff03c
author Daniel Scheller <d.scheller@gmx.net> 1503504599 -0400
committer Mauro Carvalho Chehab <mchehab@s-opensource.com> 1503830161 -0400

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>