From: Richard Acayan mailingradian@gmail.com
commit 46248400d81e2aa0b65cd659d6f40188192a58b6 upstream.
The channel's rpmsg object allows new invocations to be made. After old invocations are already interrupted, the driver shouldn't try to invoke anymore. Invalidating the rpmsg at the end of the driver removal function makes it easy to cause a race condition in userspace. Even closing a file descriptor before the driver finishes its cleanup can cause an invocation via fastrpc_release_current_dsp_process() and subsequent timeout.
Invalidate the channel before the invocations are interrupted to make sure that no invocations can be created to hang after the device closes.
Fixes: c68cfb718c8f ("misc: fastrpc: Add support for context Invoke method") Cc: stable stable@kernel.org Signed-off-by: Richard Acayan mailingradian@gmail.com Signed-off-by: Srinivas Kandagatla srinivas.kandagatla@linaro.org Link: https://lore.kernel.org/r/20230523152550.438363-5-srinivas.kandagatla@linaro... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/misc/fastrpc.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/drivers/misc/fastrpc.c +++ b/drivers/misc/fastrpc.c @@ -1688,7 +1688,9 @@ static void fastrpc_rpmsg_remove(struct struct fastrpc_user *user; unsigned long flags;
+ /* No invocations past this point */ spin_lock_irqsave(&cctx->lock, flags); + cctx->rpdev = NULL; list_for_each_entry(user, &cctx->users, user) fastrpc_notify_users(user); spin_unlock_irqrestore(&cctx->lock, flags); @@ -1696,7 +1698,6 @@ static void fastrpc_rpmsg_remove(struct misc_deregister(&cctx->miscdev); of_platform_depopulate(&rpdev->dev);
- cctx->rpdev = NULL; fastrpc_channel_ctx_put(cctx); }