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firmware: imx: warn on unexpected RX

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The imx_scu_call_rpc function returns the result inside the
same "msg" struct containing the transmitted message. This is
implemented by holding a pointer to msg (which is usually on the stack)
in sc_imx_rpc and writing to it from imx_scu_rx_callback.

This means that if the have_resp parameter is incorrect or SCU sends an
unexpected response for any reason the most likely result is kernel stack
corruption.

Fix this by only setting sc_imx_rpc.msg for the duration of the
imx_scu_call_rpc call and warning in imx_scu_rx_callback if unset.

Print the unexpected response data to help debugging.

Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
Acked-by: Anson Huang <Anson.Huang@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
This commit is contained in:
Leonard Crestez 2019-09-04 10:54:58 +03:00 committed by Shawn Guo
parent 54ecb8f702
commit cf0fd40445
1 changed files with 9 additions and 1 deletions
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10
drivers/firmware/imx/imx-scu.c
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@ -107,6 +107,12 @@ static void imx_scu_rx_callback(struct mbox_client *c, void *msg)
struct imx_sc_rpc_msg *hdr;
u32 *data = msg;
if (!sc_ipc->msg) {
dev_warn(sc_ipc->dev, "unexpected rx idx %d 0x%08x, ignore!\n",
sc_chan->idx, *data);
return;
}
if (sc_chan->idx == 0) {
hdr = msg;
sc_ipc->rx_size = hdr->size;
@ -165,7 +171,8 @@ int imx_scu_call_rpc(struct imx_sc_ipc *sc_ipc, void *msg, bool have_resp)
mutex_lock(&sc_ipc->lock);
reinit_completion(&sc_ipc->done);
sc_ipc->msg = msg;
if (have_resp)
sc_ipc->msg = msg;
sc_ipc->count = 0;
ret = imx_scu_ipc_write(sc_ipc, msg);
if (ret < 0) {
@ -187,6 +194,7 @@ int imx_scu_call_rpc(struct imx_sc_ipc *sc_ipc, void *msg, bool have_resp)
}
out:
sc_ipc->msg = NULL;
mutex_unlock(&sc_ipc->lock);
dev_dbg(sc_ipc->dev, "RPC SVC done\n");