[PATCH 02/15] ASoC: Intel: avs: Fix potential RX buffer overflow

[Cezary Rojewski]

If an event caused firmware to return invalid RX size for
LARGE_CONFIG_GET, memcpy_fromio() could end up copying too many bytes.
Fix by utilizing min_t().

Reported-by: CoolStar <coolstarorganization at gmail.com>
Fixes: f14a1c5a9f83 ("ASoC: Intel: avs: Add module management requests")
Signed-off-by: Cezary Rojewski <cezary.rojewski at intel.com>
---
 sound/soc/intel/avs/ipc.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/sound/soc/intel/avs/ipc.c b/sound/soc/intel/avs/ipc.c
index 020d85c7520d..77da206f7dbb 100644
--- a/sound/soc/intel/avs/ipc.c
+++ b/sound/soc/intel/avs/ipc.c
@@ -192,7 +192,8 @@ static void avs_dsp_receive_rx(struct avs_dev *adev, u64 header)
 		/* update size in case of LARGE_CONFIG_GET */
 		if (msg.msg_target == AVS_MOD_MSG &&
 		    msg.global_msg_type == AVS_MOD_LARGE_CONFIG_GET)
-			ipc->rx.size = msg.ext.large_config.data_off_size;
+			ipc->rx.size = min_t(u32, AVS_MAILBOX_SIZE,
+					     msg.ext.large_config.data_off_size);
 
 		memcpy_fromio(ipc->rx.data, avs_uplink_addr(adev), ipc->rx.size);
 		trace_avs_msg_payload(ipc->rx.data, ipc->rx.size);
-- 
2.25.1