Fixed a critical bug, allowing to crash the whole system with a specially crafted LoRa frame #15355
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benpicco
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Area: network
benpicco
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| if (len > 0) { | ||
| dev->driver->recv(dev, radio_payload, len, &packet_info); | ||
| semtech_loramac_radio_events.RxDone(radio_payload, | ||
| len, packet_info.rssi, | ||
| packet_info.snr); | ||
| } /* len could be -EBADMSG, in which case a CRC error message will be received shortly */ |
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Ok so CI says we can now reduce the scope of radio_payload as it's only used within the branch.
However, to avoid excessive nesting we might as well do
Suggested change
| if (len > 0) { | |
| dev->driver->recv(dev, radio_payload, len, &packet_info); | |
| semtech_loramac_radio_events.RxDone(radio_payload, | |
| len, packet_info.rssi, | |
| packet_info.snr); | |
| } /* len could be -EBADMSG, in which case a CRC error message will be received shortly */ | |
| /* len could be -EBADMSG, in which case a CRC error message will be received shortly */ | |
| if (len < 0) { | |
| break; | |
| } | |
| dev->driver->recv(dev, radio_payload, len, &packet_info); | |
| semtech_loramac_radio_events.RxDone(radio_payload, | |
| len, packet_info.rssi, | |
| packet_info.snr); |
that should make CI happy as well.
|
Seems that the same problem is mentioned in issue #14962. |
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Contribution description
As sometimes SX127x driver can return a -EBADMSG from recv(), it is necessary to check the returned value. Currently len is size_t, which expands to unsigned int at least on ARM Cortex-based platforms, causing the -EBADMSG to be interpreted as an (insanely) large value. The subsequent call to recv() overwrites all the memory available, causing a HardFault.
Testing procedure
Whenever LoRaMAC is ready to receive, send a frame with corrupt CRC. The version without a fix will crash.
Issues/PRs references