[PATCH AUTOSEL 5.4 108/130] iwlwifi: pcie: validate RX descriptor length

[Sasha Levin]

From: Johannes Berg <johannes.berg@xxxxxxxxx>

[ Upstream commit df72138de4bc4e85e427aabc60fc51be6cc57fc7 ]

Validate the maximum RX descriptor length against the size
of the buffers we gave the device - if it doesn't fit then
the hardware messed up.

Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx>
Signed-off-by: Luca Coelho <luciano.coelho@xxxxxxxxx>
Link: https://lore.kernel.org/r/iwlwifi.20201209231352.6378fb435cc0.Ib07485f3dc5999c74b03f21e7a808c50a05e353c@changeid
Signed-off-by: Luca Coelho <luciano.coelho@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/net/wireless/intel/iwlwifi/pcie/rx.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/intel/iwlwifi/pcie/rx.c b/drivers/net/wireless/intel/iwlwifi/pcie/rx.c
index 64c74acadb998..72ec2ddcaecd4 100644
--- a/drivers/net/wireless/intel/iwlwifi/pcie/rx.c
+++ b/drivers/net/wireless/intel/iwlwifi/pcie/rx.c
@@ -1292,6 +1292,13 @@ static void iwl_pcie_rx_handle_rb(struct iwl_trans *trans,
 
 		len = iwl_rx_packet_len(pkt);
 		len += sizeof(u32); /* account for status word */
+
+		offset += ALIGN(len, FH_RSCSR_FRAME_ALIGN);
+
+		/* check that what the device tells us made sense */
+		if (offset > max_len)
+			break;
+
 		trace_iwlwifi_dev_rx(trans->dev, trans, pkt, len);
 		trace_iwlwifi_dev_rx_data(trans->dev, trans, pkt, len);
 
@@ -1349,7 +1356,6 @@ static void iwl_pcie_rx_handle_rb(struct iwl_trans *trans,
 		page_stolen |= rxcb._page_stolen;
 		if (trans->trans_cfg->device_family >= IWL_DEVICE_FAMILY_22560)
 			break;
-		offset += ALIGN(len, FH_RSCSR_FRAME_ALIGN);
 	}
 
 	/* page was stolen from us -- free our reference */
-- 
2.27.0