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Commit e793f836 authored by Hu Wang's avatar Hu Wang Committed by Gabriel Biren
Browse files

Fix sub-underfow when converting scan result's age from ms to us 

Commit 5a441fcf ('Fix mul-overflow when converting scan result's
age from ms to us') fixes mul-overflow, but still sub-underflow
can happen in same line due to data type is u64, fix this by
moving check to earlier lines to ensure the sub does not results
in a negative value.

Bug: 387187200
Test: m
Change-Id: I81035e749d627fa3a7901b672241488963f3e046
parent eaabd037

wifi/aidl/default/aidl_struct_util.cpp

+4 −3
Original line number Diff line number Diff line
@@ -3895,12 +3895,13 @@ bool convertCachedScanResultToAidl(const legacy_hal::wifi_cached_scan_result& le 
        return false;

    }

    *aidl_scan_result = {};

    aidl_scan_result->timeStampInUs =

            ts_us - (static_cast<uint64_t>(legacy_scan_result.age_ms) * 1000);

    if (aidl_scan_result->timeStampInUs < 0) {

    // Ensure that subtracting does not result in a negative value

    uint64_t age_us = static_cast<uint64_t>(legacy_scan_result.age_ms) * 1000;

    if (ts_us < age_us) {

        aidl_scan_result->timeStampInUs = 0;

        return false;

    }

    aidl_scan_result->timeStampInUs = ts_us - age_us;

    size_t max_len_excluding_null = sizeof(legacy_scan_result.ssid) - 1;

    size_t ssid_len = strnlen((const char*)legacy_scan_result.ssid, max_len_excluding_null);

    aidl_scan_result->ssid =