The cec_devnode struct has a lock meant to serialize access
to the fields of this struct. This lock is taken during
device node (un)registration and when opening or releasing a
filehandle to the device node. When the last open filehandle
is closed the cec adapter might be disabled by calling the
adap_enable driver callback with the devnode.lock held.
However, if during that callback a message or event arrives
then the driver will call one of the cec_queue_event()
variants in cec-adap.c, and those will take the same devnode.lock
to walk the open filehandle list.
This obviously causes a deadlock.
This is quite easy to reproduce with the cec-gpio driver since that
uses the cec-pin framework which generated lots of events and uses
a kernel thread for the processing, so when adap_enable is called
the thread is still running and can generate events.
But I suspect that it might also happen with other drivers if an
interrupt arrives signaling e.g. a received message before adap_enable
had a chance to disable the interrupts.
This patch adds a new mutex to serialize access to the fhs list.
When adap_enable() is called the devnode.lock mutex is held, but
not devnode.lock_fhs. The event functions in cec-adap.c will now
use devnode.lock_fhs instead of devnode.lock, ensuring that it is
safe to call those functions from the adap_enable callback.
This specific issue only happens if the last open filehandle is closed
and the physical address is invalid. This is not something that
happens during normal operation, but it does happen when monitoring
CEC traffic (e.g. cec-ctl --monitor) with an unconfigured CEC adapter.
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Cc: <stable@vger.kernel.org> # for v5.13 and up
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Linux 5.16-rc4
* tag 'v5.16-rc4': (984 commits)
Linux 5.16-rc4
KVM: SVM: Do not terminate SEV-ES guests on GHCB validation failure
KVM: SEV: Fall back to vmalloc for SEV-ES scratch area if necessary
KVM: SEV: Return appropriate error codes if SEV-ES scratch setup fails
parisc: Mark cr16 CPU clocksource unstable on all SMP machines
parisc: Fix "make install" on newer debian releases
sched/uclamp: Fix rq->uclamp_max not set on first enqueue
preempt/dynamic: Fix setup_preempt_mode() return value
cifs: avoid use of dstaddr as key for fscache client cookie
cifs: add server conn_id to fscache client cookie
cifs: wait for tcon resource_id before getting fscache super
cifs: fix missed refcounting of ipc tcon
x86/xen: Add xenpv_restore_regs_and_return_to_usermode()
x86/entry: Use the correct fence macro after swapgs in kernel CR3
fget: check that the fd still exists after getting a ref to it
x86/entry: Add a fence for kernel entry SWAPGS in paranoid_entry()
x86/sev: Fix SEV-ES INS/OUTS instructions for word, dword, and qword
powercap: DTPM: Drop unused local variable from init_dtpm()
io-wq: don't retry task_work creation failure on fatal conditions
serial: 8250_bcm7271: UART errors after resuming from S2
...
smatch warns about data->list not being removed from list:
drivers/media/cec/core/cec-adap.c:926 cec_transmit_msg_fh() warn: '&data->list' not removed from list
It is a false warning, but it doesn't hurt to make the code more robust
and safely unhook data->list and data->xfer_list together with a WARN_ON
if this is actually ever needed (this really shouldn't happen).
Note that fixing the data->list warning just replaced it with a new similar
warning for data->xfer_list, so both needed to be addressed.
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
When the reply for a non-blocking transmit arrives, the sequence
field for that reply was never filled in, so userspace would have no
way of associating the reply to the original transmit.
Copy the sequence field to ensure that this is now possible.
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Fixes: 0dbacebede ([media] cec: move the CEC framework out of staging and to media)
Cc: <stable@vger.kernel.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Linux 5.9-rc7
* tag 'v5.9-rc7': (683 commits)
Linux 5.9-rc7
mm/thp: Split huge pmds/puds if they're pinned when fork()
mm: Do early cow for pinned pages during fork() for ptes
mm/fork: Pass new vma pointer into copy_page_range()
mm: Introduce mm_struct.has_pinned
mm: validate pmd after splitting
mm: don't rely on system state to detect hot-plug operations
mm: replace memmap_context by meminit_context
arch/x86/lib/usercopy_64.c: fix __copy_user_flushcache() cache writeback
lib/memregion.c: include memregion.h
lib/string.c: implement stpcpy
mm/migrate: correct thp migration stats
mm/gup: fix gup_fast with dynamic page table folding
mm: memcontrol: fix missing suffix of workingset_restore
mm, THP, swap: fix allocating cluster for swapfile by mistake
mm: slab: fix potential double free in ___cache_free
Documentation/llvm: Fix clang target examples
io_uring: ensure async buffered read-retry is setup properly
KVM: SVM: Add a dedicated INVD intercept routine
io_uring: don't unconditionally set plug->nowait = true
...
Make the code a bit more robust by checking if the adapter has
been unregistered at the start of cec_transmit_msg_fh() and
cec_received_msg_ts(). If it is unregistered, then just return.
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
For some inexplicable reason I decided to call flush_scheduled_work()
instead of cancel_delayed_work_sync(). The problem with that is that
flush_scheduled_work() waits for *all* queued scheduled work to be
completed instead of just the work itself.
This can cause a deadlock if a CEC driver also schedules work that
takes the same lock. See the comments for flush_scheduled_work() in
linux/workqueue.h.
This is exactly what has been observed a few times.
This patch simply replaces flush_scheduled_work() by
cancel_delayed_work_sync().
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Cc: <stable@vger.kernel.org> # for v5.8 and up
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
The cec_adapter struct contained a waitq field that isn't used
anywhere, so drop this.
It also contained a phys_addrs array to store any reported physical
addresses. However, this was never actually used, so this field is
removed as well. The original idea was to let the core keep track of
this information, but nothing was ever done with this. Should this
be needed in the future then it is easy enough to resurrect this.
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
The log_addrs->log_addr_type[i] value is a u8 which is controlled by
the user and comes from the ioctl. If it's over 31 then that results in
undefined behavior (shift wrapping) and that leads to a Smatch static
checker warning. We already cap the value later so we can silence the
warning just by re-ordering the existing checks.
I think the UBSan checker will also catch this bug at runtime and
generate a warning. But otherwise the bug is harmless.
Fixes: 9881fe0ca1 ("[media] cec: add HDMI CEC framework (adapter)")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
In preparation for moving CEC drivers to the CEC directory,
move the core to a separate place.
Acked-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
