From: Enrico Granata egranata@chromium.org
[ Upstream commit 94d4e7af14a1170e34cf082d92e4c02de9e9fb88 ]
As new transfer mechanisms are added to the EC codebase, they may not support v2 of the EC protocol.
If the v3 initial handshake transfer fails, the kernel will try and call cmd_xfer as a fallback. If v2 is not supported, cmd_xfer will be NULL, and the code will end up causing a kernel panic.
Add a check for NULL before calling the transfer function, along with a helpful comment explaining how one might end up in this situation.
Signed-off-by: Enrico Granata egranata@chromium.org Reviewed-by: Jett Rink jettrink@chromium.org Signed-off-by: Enric Balletbo i Serra enric.balletbo@collabora.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/platform/chrome/cros_ec_proto.c | 11 +++++++++++ 1 file changed, 11 insertions(+)
diff --git a/drivers/platform/chrome/cros_ec_proto.c b/drivers/platform/chrome/cros_ec_proto.c index a0b8c8a8c3231..5c285f2b3a650 100644 --- a/drivers/platform/chrome/cros_ec_proto.c +++ b/drivers/platform/chrome/cros_ec_proto.c @@ -66,6 +66,17 @@ static int send_command(struct cros_ec_device *ec_dev, else xfer_fxn = ec_dev->cmd_xfer;
+ if (!xfer_fxn) { + /* + * This error can happen if a communication error happened and + * the EC is trying to use protocol v2, on an underlying + * communication mechanism that does not support v2. + */ + dev_err_once(ec_dev->dev, + "missing EC transfer API, cannot send command\n"); + return -EIO; + } + ret = (*xfer_fxn)(ec_dev, msg); if (msg->result == EC_RES_IN_PROGRESS) { int i;